But isn't that what destroyed the game? It was simply turned into ruins from randomly placed blocks, besides, initially the levels were quite normal, both in terms of design and complexity, but now they are just ruins, as I said earlier.
TL;DR: the game is a difficulty arms race amongst pro players that either make it harder or easier for future players and it is expected that difficulty will cancel out over time. The game isn't dead as this motivation to make the game harder/easier forces new mechanics to be found and used. Even bugs.
Well yes, the game will naturally continue to become difficult but with the current hardcore players making efforts to make the game easy with other players who make the game difficult, they will naturally create ways to allow players to bypass each other.
Layering blocks on top of eachother makes removal a waste to those who want to make paths AND those who want to destroy easy ways out. It can make walls that block areas and since griefing tends to happen in the early stages and those who want to make it easier discovered that if you collect a building checkpoint, don't build and go to a lower level that you didn't build in, you gain more builds.
Now if you want to grief the lower levels, you first need to waste your builds making it impossible to climb down the tower then are forced to use a minimal amount of blocks to build with. For those who make levels easier, they can undo these attempts at closing areas to make them 1 way in while using the builds to make significantly easier paths.
The ice level is one of the easiest levels because griefers try to go to lower levels which forces them to make many downward paths (beating the game saves your edits to the game). Since those who make the levels easier can always beat the game by skill + making the difficulty easy they can make NUMEROUS changes that get saved.
Of course a DEDICATED griefer with amazing skills (or even hackers) can beat the game with an absurd difficulty but there will always be proplayers (even good hackers) that will undo these changes.