Because of all of all of the new players to D2 through D2R I felt there is a need to create such a thread. To answer the question I first have to set it up.
I will call public multiplayer (non private multiplayer) as pickup groups (pugs for short).
The term pugs is well known in the MMO community. Random pugs are not good to join in a variety of games for a variety of reasons. In some games they have their niche uses though.
But in D2R they have two problems that will prevent you from joining them. One is hostility (PvP), after level 9 a player can declare hostility on another player in a party. Doing so will cause that one to leave the party. Not sure if anyone in the party can fight the one that went hostile or not.
The second thing is loot. The loot is FFA so it drops for anyone to pick up. The problem is that some cheat using a script to help them pick up loot faster than what any human being can do.
Actually though multiplayer whether random pugs (non private multiplayer) along with private multiplayer is better for experience and solo mf runs are better for loot.
Now if you want to play multiplayer but don’t want the hassles of FFA loot being picked up by others or don’t want to handle players going hostile on you. Then by all means play in private groups. There are many ways to make friends in a game both in the game and outside of the game. Then play private games where you know they won’t do those things. Where they agree to share the loot as well.
There are other games out there that have modes or systems that are just not for every player nor should they be. Trying to design them for that, such as D2R, will destroy the authenticity of the original D2R experience.
D2R was design to be a game for carebears or a game to hold players hands.