I noticed on an old forum post from 2016 you mentioned that you were working on the ability to merge theme style sheets with the microthemer style sheet so there was only one (rather than having duplicates). Is this still going to happen? Or has it happened and I never heard about it?
Could you send me a link to that forum post? If you mean concatenate all site stylesheets into one, I’m not planning on adding that feature, even if I was once. There are many plugins dedicated to that, and related site performances. I use Autoptimize for concatenating stylesheets into one (and minifying). Tip: remember to clear the cache after making changes in MT if using such a plugin.