FreeBSD Linux emulation is being developed for 20 (may be even 30) years. While Apple can throw some $$$ to get it implemented in a couple years using virtualisation requires much less development time (so it’s cheaper).

Apple's already got the Virtualization framework and hypervisor already (https://developer.apple.com/documentation/virtualization), so adding the rest of the container ecosystem seems like a natural next step.

It puts them on par with Windows that has container support with a free option, plus I imagine it's a good way to pressure test swift as a language to make sure it really can be the systems programming language they are betting that it can and will be.

OrbStack has a great UX and experience, so I imagine this will eat into Docker Desktop on Mac more than OrbStack.

Because that‘s a huge investment for something they have no reason or desire to productivize.