Technically, it was raid or die, or possibly PvP or die, as far as gear, the thing that made it popular was there were open world reps that provided other things that people could work on instead of gear.
Netherwing rep, the dragon races in Shadowmoon, Orgri’la, etc.
The thing is, since Wrath, we had more devs, or whatever, that seemed to think raids and such were not being done due to gear, so they started inflating access to gear. The thing is, vanilla, BC, Wrath, and even later, hac activities that people could do for other rewards aside from gear, it was these activities that drove the popularity.
Sadly, the bottle of the genie has been opened as far as world content providing power progression, and it is a PITA to stuff the genie back into the bottle. Maybe the goal of DF is it get the game closer to the roots of what was established in vanilla, BC, and wrath while not completely retuning to those days.
Because there is none outside what you can get via rep up to a certain point. Vanilla, TBC and Wrath were the days where gear was available more in instanced content, but the devs were able to make the open world FUN. Then wow started to move into the idea that only instanced content should be “fun” and slowly (as there were still things like IoT/IoG and timeless) made the open world boring, easy and all in all, just something the devs thought should be a stepping stone.
Maybe the issue is now we have the arguments of “if you are not going to make the content fun, make it rewarding” or “if you are not going to make it rewarding, make it fun” for those of us that have played since vanilla.