Don't forget that the F4 film Is not set in the same universe as the rest of the MCU (yet). If they wanted to explore this storyline in the future they'd simply need to pull an alternate universe version of Manor from the infinity hat. That's what they've been doing for dealing with continuity issues in the latest movies.

I might be mistaken, but as far as I , at least in the Italian translation of the comics, Thanos has stated a long time ago that the gems work better when they are connected, and that one gem in particular can empower another, following a rock, paper, scissor logic. The gauntlet is the medium that allows his connection.