Talents; if everyone min/maxed in the same way, output talent options would not be different in the slightest, at all. There would be 0 need to have 3 talent options to pick from for damage/healing output. There’s a lot more fun talents that aren’t absolutely optimal but change the way a spec plays and makes it more fun to players.
It is not needed. If you are not doing world first, very few bosses absolutely need you to min/max to the degree some people min/max. This is a game, not a full time job, stop treating it as such unless you’re being paid for it or that’s your cup of tea. More than half of the bosses in raids require mechanics over super high dps, this has been the case since WoD. maybe even MoP when thunderforging and tokens were introduced.
Raids get nerfed. Back in the older xpacs like WotLK, BC, Cata you did not have gear coming in from other sources except raiding and PvP. I think there might have been some crafted gear, too, but I think it also required raiding or so much farming. Point being, there wasn’t so much excessive gear coming in. If your guild could not down a boss, then it was stuck. A lot more DPS check bosses were around plus they required a lot better performance for mechanics while keeping DPS to a high degree. They realized this hampered a lot of guilds, so they made things easier over time.
By easier I do not mean more mechanically easier, they loosened the requirement to down bosses. Instead of super high dps+mechanics performance on the part of every single person, it is now more mechanics heavy than damage output. Also, you did not have so much gearing options then, which actually works to soft nerf raids each week.
Think about your weekly mythic+ for doing a +15. That’s a guaranteed piece of mythic loot each week. Whether it’s an upgrade, side grade, or nothing at all is entirely different, but it is a guaranteed piece of loot right there without ever having stepped foot into the raid yet. Across 20 raiders? This is 20 pieces of gear, that’s a lot of potential soft nerfing. Bonus rolls added in many more gear drops. Titanforging/Corruption added bonus output for free. In Legion they tuned raids to be set for everyone in the raid having a minimum of X level of weapon traits. If you had more then that was extra bonuses. They tuned BFA raids to a minimum neck level, more is again bonus output. Bonuses on top of bonuses on top of more bonuses to reduce the difficulty of the raids.
Yes, guilds still do not complete Mythic, more of that is usually player skill levels than anything else, as a lot of people still fail at mechanics. That is both player skill and mechanics, not because they do not meet the damage output required, but usually a failed mechanic turns into a raid wipe.
With all this, do you feel you have to min/max? Absolutely not. If you want to, sure go for it, but your characters, in most cases should be more than capable of downing the boss before an enrage timer, assuming people do mechanics correctly and not mess those up. DPS checks are a different story, but again, a lot fewer of those when compared to the raid as a whole.