You start by saying it isn’t a genuine argument and then admit Qualcomm has been bad at this for a while..
"Linux 6.2 Expands Support For More Qualcomm Snapdragon SoCs, Apple M1 Pro/Ultra/Max"
https://www.phoronix.com/news/Linux-6.2-Arm-SoC-Updates
"Qualcomm Snapdragon 8 Gen 2 Patches Already Surfacing For The Linux Kernel" https://www.phoronix.com/news/Snapdragon-8-Gen-2-Linux
"Qualcomm Snapdragon 8 Gen 1 Sees Timely Support With The Mainline Linux 5.17 Kernel"
Stock android? Yes, perhaps. Some functionality from devices is provided via closed firmware blobs that you'll need too. I'm thinking of the modem or other DSPs at least. However I suppose that projects like LineageOS just harvest those from working phones?
I know one developer at Qualcomm who uses Linux on their Snapdragon laptop.
IMO the blobs aren't very objectionable while still not ideal. Would I prefer to have the source to software running on all the peripherals? Sure, I would. But once you're programming on the peripherals it narrows significantly the audience who's interested and capable at changing behavior or making fixes.
I could be wrong but I think this is actually somewhat common.
This talk is a great overview of where things are going...