Linux is fragmented. Windows has shockingly few indie devs given its marketshare (compared to Apple: Omni apps, Structured, Day One, Session, Pixelmator, Fantastical...). The Mac has plenty of eager indies that care deeply about UX and design, and many discerning users who care too. Caring about UX/design is their "carrot"; they don't need the "stick" (deprecation).
The stick was mainly necessary for big devs back in the day, who never cared about making Mac-assed Mac apps. Now those have switched to Electron anyway; the stick no longer provides meaningful incentives. It just annoys people who want to play Half-Life for 5 minutes every few years.
I'm sure the people on the Mac team think exactly the way you do though, so I guess I hope they read this, or at least that they make sure their assumptions are still valid.