Few catchup mechanics though, now you can literally not play the whole expansion, jump in the last patch and get almost as good gear as those who have played the whole time, in a couple of weeks due to catch up mechanics making EVERYTHING previous to current content trivial and useless.
In Vanilla you'd need to grind dungeons to get ready for raid (not talking about classic where we knew what we where doing, and thus oneshot MC with questing greens and class stacking). Then use MC gear to prepare for BWL and so forth. Sure dungeon gear got an upgrade in 1.12 (which is the patch Classic is at), so there was some kind of catch up from that. But it was a grindy slope of gear, which made it a far more rewarding system for a lot of people.
The downside with such a system is that if you're not raiding, you will have to find a group for the lower raids to get into raiding. So you can't really get a spot in a current raid guild, you'd need to PUG your way up or find a guild interested in boosting you through MC, ZG and BWL to get you ready for AQ40 (and to help you farm NR gear if needed).
Now you log in on your new alt for 8.12 or what ever patch it is now (I dont play retail anymore), do the new catch-up mechanig, and get your ilvl in order so you can start spammnig m+ for upgrades. Then pug what ever raid there is on normal, get decent logs and apply for an HC or Mythic guild.
Both system got their ups and downs.