There actually isn't any reason STM or NXP or whatever ARM vendor couldn't provide AVR-like usability and awesome libc. For example the assembly blobs used on m

There actually isn't any reason STM or NXP or whatever ARM vendor couldn't provide AVR-like usability and awesome libc. For example the assembly blobs used on most STM32s are very simple. It's simply that they want to push people to their propietary IDEs (to increase vendor lock in). STM used to provide an okayish libc implementation but then decided to bury it inside CUBE (MX). If your design becomes complicated enough sure go ahead and change the startup code. But that's quite a small portion of all uses and for those we should have AVR like ease of use.