so here is the deal: ive been playing since bfa and i tried pretty much all kinds of content, ive played PVP (i suck at it), raiding, roleplaying and the thing ive found most entretaining is actually alt leveling, i enjoy leveling and getting my hands on every single thing i can from the old content and also playing the actual content, but while i enjoy raiding im kind of an lonely wolf, dont get me wrong, i like chatting with people but while im playing i prefer to do my own thing while i listen some playlists, however many of my friends criticizes me because they say that WOW is a social game and im not actually playing if i dont do some guild content, but many of the times ive been on guilds are eather hardcore raiding guilds that destroy you if you dont play the spec that is in the top tiers of the charts and treat you like garbage if you dont do a minimal amount of dmg in raids, or extremely goofy guilds where are constanty doing silly stuff, and yaeh, to each their own, i dont think they are wrong for doing that but thats just not my thing, si i guess my question is: do i really miss something important for not joining a guild or not?
Im in my guild purely for having people to talk to.
Although with how dead the game has become, conversation has become pretty sparce.
Really the only thing you lose out on is guild perks such as a faster hearthstone cooldown.
If you dont want to raid, dont raid.
The game is great for going solo.
Soloing is fine.
Also periods.
nah guilds are nothing like they used to be. and you ain’t trying to do group content like raid or keys so your good.
its a multiplayer game, that rewards you for team play, sure you can pug, but in most cases you will never find the meaningful connections this style of game is prided on by being a solo player, but if you dont care you will be “fine” but having a team will always get you further faster
In 2005, guilds were great, players were fun, game was social.
In 2023, guilds are dead, dying or elitist. You’re not missing anything.
guilds are just too much drama.
play how you want.
Only time you should join a guild is if you bother doing any end game PVE since I think endgame PVE is about as fun as getting kicked in the crotch I’d say guilds are pretty worthless.
Guilds do offer some benefits
Social interaction
Useful abilities
Bankspace
etc.
I feel it is not 100% needed, but nice to have.
Raiding and mythic+progression…potentially missing out.
World pvp and arena, potentially missing out
World content… probably not
Nothing you’re missing out on couldn’t be solved by being savvy about the game and making your own groups or joining ones where you vet the people in it. If you don’t have the knowledge or skill, then guilds could potentially be helpful to do it for you.
Guilds just make it easier to vet because you already know them
Not all guilds are created equal, and it will depend upon the average skill of said guild
Guilds were great back when they had perks. Mass summon, xp boosts, etc.
yeah, like i said i actually enjoy raiding, what i dont enjoy is hardcore raiding, tbh the thing i do most of the time is eather transmog or mount hunts, im trying to have alts from every race doing some lore accuarate race/class combos and trying to get the perfect set/mount for each one of them, im also trying to get every cosmetic thing that i can get from old content, i considered forcing myself to do pvp and arenas for the mounts you get and some sick transmogs but i dont enjoy it at all, pvp is not really my thing, and my problem with raiding is that most of the times i get into groups where they treat you like crap if you dont fill their expectations, so i reached a point where i realized that i can pretty much get almost all the cosmetics from a recent expansion waiting for the next one to come out and doing it myself
Its clear from your post that you do not do group content or care to talk to people so why would you even thing about joining a guild?
Go form your own and you will unlock the few guild perks there are from the old content you are playing so there really is no reason at all to join an existing one. In fact, making your own will serve you more because you can unlock the guild bank for more storage and even have your alts join it and use it as shared storage.
The short answer is no.
You can pretty much do any and all content in the game without being in a guild and guilds don’t give any kind of advantage like they used to in older xpacs, so if you don’t want join a guild don’t. And don’t let anyone pressure you into it.
If you can find a nice casual guild with helpful players it can be nice. The best perk about a guild though is the hearth reduced cooldown.
There are some guilds which focus just on people who like leveling. We had a guy like that in my previous guild which I was in for over 10 years. He did nothing but level. When he reached max level, he deleted that character and started another. Not my thing, but that was his thing. He was a great guy and we loved him. Brought him to raid just one time when he wanted to see what it was like. He said “that was cool”, then promptly deleted the max level character after and went back to leveling. 
(I can say thank heavens for when btag friending came out because it made it MUCH easier to keep track of him when he made new characters and get him invited back to the guild. )
Also, as others have pointed out, there are more opportunities to be social with a group of people you’ve gotten to know if you’re in a guild. Personally, I prefer being in a guild.
As for guilds, I have been in many of them.
Some were very small, like my current Alliance guild. I am the only one in it. All 25 of my Alliance Characters.
Others have been very large. I have a Horde character that is in a guild of nearly 1000 characters,
Sometimes in this Horde Guild there are 25 to 30 players on and guild chat is totally silent for hours on end, everyday.
Even Trade Chat is that silent.
Social Game? I do not see it anymore.
Nope. Make your own guild like I did and enjoy the extra bag space
Do yourself a solid. Make a guild yourself, your own personal guild, so you will reap the benefits it brings, and avoid those obnoxious automated spam guild invites.
Honestly you lose quite a bit. Access to bonus resources from a strictly practical standpoint, but also, a community is ultimately what keeps people in games like these. By yourself, you’ll eventually lose interest and move on to something else, especially if you don’t have a raid group to work towards.