Thanks for bumping this question!
Part of the reason is that working with Multisites is very tricky and there are lots of nuances to migrating a site between environments. This sort of complexity is the primary reason that Local doesn’t have any sort of automated way of doing it currently.
I totally agree. Do the steps in this post give you enough to go on? Either way, I’ll put some time on my calendar to write up a more formal thing and publish it as a help doc.