rm -r fs/ext3

Bit rot. There is always some extra modern tool you need to compile (like ddrescue). And it need modern library deps too. The GCC for userspace is built with headers for some kernel version, forcing you to have an old toolchain too. And then it turns out that doesn't compile or run because the ABI changed. All of a sudden you're in an all-out legacy land trying to make things compile. That is usually a waste of time compared to just using the latest of everything, like you do every day.