Everquest was great because of the people- Older MMOs were made where you could excel at a class, get a reputation (for good or ill) and they had actual communities. They werent necessarily end game gear grinds.
They were, dont lie now ... EQ had notorious grinds and people accepted then because it was "the end game".
A lot of stuff remains from old MMOs, the mythical "endgame" is one and EQ was basic quests, the game that really broke that mold was WOW but it was already heavily set by the Warcraft games so it could do that, MMOs simply could not easily establish such lore and often that lore was completely ignored by the players that simply were on the gearing treadmill, WOW is included on that.
Also I have to point out the grind of those MMO ended up going in a very stupid direction, FF XI had a boss that took 18 hours to kill and many MMO (pre-WOW model) were going down the same path, the whole "actual communities" is simply the chat, things are different now simply now because on those old days the chat was about it but then come all those private chat servers that guilds started to use that leads to today were people have Discord or other VoIP systems because ... the old MMO created bosses you need a guild and coordination to kill and the game chat wasnt suitable for then and thus they created the 3rd party segregation that exists today, if anything EQ is directly responsible for the death of game communities as it make people use those systems and not their chat system, even if to be fair EQ didnt exactly did on purpose outside creating gameplay that required the use of such tools.
The "genre" evolution into what is today is caused by what those old MMOs did, they pushed for harder bosses and more grind with WOW not being revolutionary but evolutionary with pre-WOW MMO simply going into other more extreme areas as WOW was a typical Blizzard product of the that time, blaming "mainstream" is retarded as L2 had a much bigger playerbase that EQ and took some time before WOW catched up to L2 numbers, the system is what is today because costs. I dont like the current model because is fucking predatory and designed to annoy the crap out of you until you pay however this is current year in gaming were you can sell that BS is most AAA releases, we used to have cheat codes and now we have to pay for cheats ... fuck, we have to pay for mods with a cut going into the publisher.