Why were there so few and what were they anyway?
There was Wurm online which was a complicated messy sandbox MMO. I also remember plenty of physics and combat sandboxes in the Flash space. Sim City was a city builder sandbox. As for block building sandboxes there was Infiniminer.
As for survival, many games have had survival elements. A core mechanic of roguelikes is something called a hunger clock. It doesn’t necessarily have to be food based but the idea is a game that is about exploration and conquest having a mechanic that limits exploration creating tension where you have to explore with purpose instead of meandering. Some MUDs might be able to be seen as precursors to massively multiplayer survival games like Rust.