Four years ago I bought a OnePlus 2 for 319€, nowdays it still is good hardware, it's better or as good as most of the mid to low end phones in the market.
But it has a big-ish problem, it is stuck on Android 6, which not only is old and probably full of security holes, it is starting to not be supported by some apps.
It provides Android 10 for my phone and works flawlessly (from what i can see, only been using it for 4 days), so the fact that "some randos" (with all my love, I'm a rando) can make it work, means that the manufacturer could have if they wanted, they just chose not to.
It's really sad because if i wasn't a geek that knew how to put LineageOS on the device i would have probably ended up buying a new phone, making the world be fill with more junk.
Let's hope the more open devices like the PinePhone KDE Community Edition put an end to this :)