Adobe is a great company and for sure has great developers on its sleeve. It would cost them much less than 20B to develop a Figma clone and just offer it as part of their suite, they wouldn't have an issue positioning it in the market. Heck, with about a million and a talented team you could build a pretty decent Figma alternative, so why did Adobe pay an extra 19,999(!) million?
Is it the community? The brand? Didn't want to risk it? To put them out of bussiness (just as Adobe could've made Figma, Figma as well could've started building their own Illustrator, Photoshop, etc...)? So, why?