If you buy the argument, you obviously never gamed during the 90's during the heyday of level editors, free maps and mods over IPX emulators like Kali and kahn.
It's not utter nonsense, DRM is literally taking files of the game hostage. Go load up overwatch and disable the network card, Go load up quake 3 or Unreal tournament 2004.
You can still play Quake 3 and UT2004, you'll notice a big fat error in overwatch because it is logging you into a server required for it to function.
Go get never winter nights released in 2002, compared against the "f2p" (aka stolen rpg rebadged an f2p mmo during develpment).
https://store.steampowered.com/app/704450/Neverwinter_Nights...
The original neverwinters had game tools and you could run your own server, vs neverwinter the "f2p mmo" version (aka moniker for the game moving to server locked game).
https://store.steampowered.com/app/109600/Neverwinter/
Any gamer in the 90's was expecting more dedicated servers, level editing tools with PC games.
Leauge of legends and DOTA 2 would have been fully single player RTS games with multiplayer.
So no you and anyone who believes like you is willfully ignorant that we now live in a PC game dystopia. Whereas before League of legends and DOTA 2 would have been coded like Quake 3, Unreal tournament 2004, and warcraft 3, you own the game and can play it multiplayer if necessary without a third party.
Diablo 2 we owned it --> Diablo 3 blizzard owns it and can now shut it down
Quake 3 we owned it --> Quake champions bethesda owns it and can shut it down.
So no, we've gone backwards in time to mainframe and dumb client model of computing because of the average gamer being computer illiterate and not seeing the writing on the wall.
So no they were not fundamentally a new "genre" that was what marketing and PR flackeys hoped people like you would buy. Note that private servers prove you incorrect, aka that there exist private servers for Ultima online and World of warcraft, demonstrate tehy would have just been Role playing games with shards players controlled, there was no need for companies to conrol them or the monthly fee.
Overwatch is a case in point that you are incorrect, since it's just a multiplayer fps, why is there no level editors, tools, open file specs and GTKRadiant? OH yeah thats right they wanted to lock down the code from a server in their office to resell skins that are sitting on encrypted files already on your machine setting a programming flag to display, when you've "earned" them via the stupid leveling system or gambled for them using their lootbox system.