Every Arm SoC being a snowflake needing special attention by the OS is a huge hassle. There's a reason there's no simplified Arm installer for operating systems.
However… ACPI is apparently a pretty awful thing to implement. When it doesn’t work, or mistakes are made (looking at my own 13th gen HP laptop right now - borked ACPI tables means unpatchable broken sleep on Linux), then it’s pure frustration.
Device trees on the other hand are much more binary. Either everything generally works or it doesn’t at all. It’s a valid approach.
https://github.com/j0hnwang/OMEN-Transcend-16-ACPI-fix
But yes, device trees are far nicer to work with.
short-term support helps qualcomm sell more because their customers want to sell more phones to the same users. on the other hand, for the industrial partners there is an "LTS" model of support given (side effect being fairphone 5 https://news.ycombinator.com/item?id=37320800).
long-term support through backwards compatibility helps intel because they can sell new chips with the assurance that the ancient, unmaintained industrial software continues to run in a shinier box.