Oh you want a way to become invincible without having to beat a boss? Build some wooden platforms up a tree then destroy the bottom part. Done. Invincible in a few minutes.

Also occasional waves of monsters is not an equivalent to a constant threat. Even if you ignore that you can just not trigger them if you don't fulfill the wave conditions or that you can just make it so you are immune to these attacks. The fact that people build impassable moats around their bases that make the only thing you could possibly construe as a survival mechanic a non-issue should tell you that it isn't a survival game and that people actively avoid that part of the game.

Sayin: you have to do something to progress so it's a survival game is utter nonsense. That's like every game in existence. There needs to be a constant threat of some kind. If you can eliminate all threats within 5 min that doesn't really change anything.

Advancement does not matter at all.