I think placing base foundations still flattens nearby terrain? But yeah, the devs admitted that the destructible terrain was a huge mistake that caused massive pop-in and performance losses, even now after they dialed it down to nearly zero.

They couldn’t just remove voxel terrain entirely because the world is a mishmash of voxel and classic geometry. The voxel destruction/deformation only applied to the sand and soil on the ocean floor, which let players dig several feet down before hitting solid terrain. Most other terrain features are static props.

They’d have had to redo nearly the entire terrain to remake it as a traditional polygonal mesh, so instead they simply removed the player’s dig prompt and the terraformer item. I think there’s even a console command to re-enable everything? There was at some point during Early Access, at least.

I don’t recall them ever saying anything about randomly generated worlds though. It’s been bespoke since the very first alpha, though a lot of first-time players thought it was procgen due to the random spawn locations.