Yea SwiftUI being tied to the iOS runtime was an incredibly bad decision IMO. WWDC the last couple years has been mostly useless because it's all about SwiftUI, and basically none of Apple's major app partners can use it yet since we are stuck supporting iOS11/12.

edit: and most of the useful additions are tied with iOS14 (lazy lists), so even if we were able to bump our min support to iOS13 it would be _years_ before we could do 14.