Software freedom is not just about being able to run Linux. Being able to run Linux doesn't help the billions of people who will never use anything other than the stock OS that ships on their phones, tablets or computers.

I bought a model of a phone that doesn't have LineageOS support because apparently it's a weird carrier model. The base model has AOSP support, though. Didn't realize that until a few months into ownership, and by then it was too late to return. I'm stuck with Google's Android.

I've been running Linux for like 19 years now.

Ofcourse it doesn't serve the vast majority of users any good. If it would then Linux wouldn't be in minority use on desktops/laptops.

However there is a clear difference between there being the possibility to run alternative OS's on a device vs there being a convenient method to switch to something else.

Most Android devices do not force the user to use the stock OS. PC's do not care what OS they run. This runs contrary to your initial comment on users being dictated on what can and can not be run on the hardware.

Since, for the mobile industry at least, the business model doesn't revolve around simply selling hardware (Apple as well as Google makes most of their mobile earnings through the stores and ads after all) I can fully understand that that flashing with other OS's isn't supplied as an easy one click selection by the manufacturer. Why should it?

The fact that your new phone is only supported by some of the alternative software but not the one you want to use is no judgement on the manufacturer.

Not every piece of hardware should be supported by every piece of software.

Let it also be known I have run Linux for 18 years, along with various AOSP devices and other funky Linux mobiles over the last 10.