It is polite-speak for “you are very wrong”. A very common rhetorical construct.
You say all of this like we would be able to mind-read why your phones broke, and that is a well-established fact. Requirements of VoLTE had lots of Xperia X and XA2 users posting, so evidently people can keep their phones for long. And even though i have switched maybe every 18 months before now - nothing has forced me to do so in the slightest.
The 5-year of software update rules? What do they matter when SFOS has never done under 7 even before? As far as i have seen it has no bearing on parts availability.
Other shops would have accepted.
I can’t see any relevant spares for that for Fairphone either.