Your argument is more or less a critique of Swift itself, which is a far more full-featured and "safe" language than Objective-C, at the expense substantially higher compilation times given otherwise like-for-like programs.

You're not necessarily wrong, but that ship has sailed for iOS development long ago and isn't necessarily the fault of teams like Doordash who have probably (like others) already squeezed as much build-time performance out of their given app size and feature set.

Mobile apps are inherently monoliths, and there is unfortunately no real way around some code changes triggering full rebuilds of millions of LoC.