I think people have pretty well nailed it on the head here.
I don't have a problem with people terming it "MTR". Even if it's not a legal term it works fine as a distinction of something between STR and traditional true LTR in practice.
I'm not sure why you think there's something you have to be "missing" here or what sounds "too good to be true". This isn't like the early days of STRs where people are buying a few and getting rich off of it. MTR doesn't really promise too good to be true returns. Maybe a little more than LTR, for a bit more work than LTR.
I think once you factor in the cost of furnishing and utilities (both of which would be paid by the tenant in traditional LTR) as well as vacancy (it's typically not nearly as easy to find MTR tenants as a lot of people imply) the returns are probably similar to LTR, maybe a little better. One nice advantage is you'd have eyes (and cleaners) on the place more often than LTR, where you don't know what kind of disaster you're going to be walking into after a tenant has been in there for years.
So yeah, it's fine. Just because influencers have jumped on and started pumping it to make a quick buck doesn't mean it's bad. Perfectly fine strategy with reasonable expectations. If you're already buying the place you can try it out and let the rest of us know how it goes, as most of us don't really have much hands on experience with it to compare it to STR that we're very versed in.