> It's important to remember Rust's borrow checker was computationally infeasible 15 years ago.

The core of the borrow checker was being formulated in 2012[1], which is 13 years ago. No infeasibility then. And it's based on ideas that are much older, going back to the 90s.

Plus, you are vastly overestimating the expense of borrow checking, it is very fast, and not the reason for Rust's compile times being slow. You absolutely could have done borrow checking much earlier, even with less computing power available.

1: https://smallcultfollowing.com/babysteps/blog/2012/11/18/ima...