Yeah, and I think the NSMB games were in an odd spot because their general design sensibilities were closer to SMB3 (dense horizontal levels with a focus on new ideas and gimmicks, less secret exits and alternate paths, 8 worlds with similar themes/Toad Houses/etc.) but they had more safeguards akin to SMW (extra item slot, replay levels for power-ups) so they sorta straddled the line and never really felt like a full on successor to either sensibility, though I think most would characterize them as being iterative of SMB3. Whereas Wonder, very clearly, is a spiritual successor to World's ideas and philosophies (as well as aesthetics). While I prefer SMB3 to SMW, I definitely think Wonder knows what it wants to be and where it's taking the series going forward, and in many ways does feel like the lost SNES Mario platformer sequel we never got, just modernized. I also think Nintendo spent way too much time doing nostalgic SMB3 throwbacks, even as a huge fan of that game, so I'm happy with how Wonder has turned out in that regard.
Also, doesn't a game over in NES SMB3 just return you to the last checkpoint on the map? That's why toppling Fortresses unlocks the doors. I don't think it just boots you to 1-1, but I might be wrong. That makes the lack of a save battery in that game stranger, honestly.