you seem to misunderstand
yeah wow had the whole group content down but it was such a mess in the early days that was true about most of it
however compared to other MMOs it was seen as more casual than anything else and it truthfully was because you had no penalty for dying beyond repair bills and the bosses were simple enough that the biggest challenge was getting everyone to do the 1 thing right at the beginning
did it cater to the hardcore guys that liked taking trophies from the players they killed in games like neocron or rohan?? no
did it cater to the guy that kinda ignored people and did the bare minimum to get to the end of quests?? no
did it cater to the pvp gods that refused to do anything beyond world pvp?? definitely not after BGs were introduced
you act as though catering to everyone means everyone in a group but you fail to realize that even back in classic you had solo players