If I was Figma, and I had to choose, I would go with Adobe. Adobe would have made Figma a core strategic product and would have made them much more relevant in a space that they deeply care about. Microsoft would never care that much about Figma, because the design/UX space isn't core to Microsoft. Also, Figma is too small for Microsoft to make it a centrepiece of any of their strategic initiatives.
>The point is the value of not having Figma sell to its largest competitor.
Adobe does not compete with Microsoft in any meaningful way. There is some overlap in some products here or there, but it's not meaningful competition.
Microsoft seems to be pretty hands off when it comes to acquisitions. Github/LinkedIn were both a acquired and each have grown a lot since the acquisition.
It's rumored Dylan Field (CEO of Figma) approached Microsoft [1] around the same time they were talking to Adobe but Microsoft declined to make a deal at the time (seemingly due to Microsoft's then in-process $69billion acquisition of Activision Blizzard).
However, I am afraid they will sell to someone else. Namely, Microsoft.