That's what I meant, it didn't have seasons but did introduce new things that were small enough not to warp the game. I think they originally made talents have cross talent benefits so that you had a reason to take earlier talents, then they added the Diablo you can summon, and finally the realms you could enter for the three Prime Evils. It was all small bonus content that didn't fundamentally change the game.
What I don't want to see is dumb shit like WoW Mythic seasons where everything in a dungeon gets a specific ability or two for a few months or something else that warps the game. I just don't like live service crap.