I have a "desktop pc" that has a dual core Arm Cortex A7 at 1 GHz, 1 GiB of memory and a GPU that will tear the RPi to shreds. And it runs almost vanilla Ubuntu

I have a "desktop pc" that has a dual core Arm Cortex A7 at 1 GHz, 1 GiB of memory and a GPU that will tear the RPi to shreds. And it runs almost vanilla Ubuntu. But it's not usable for a desktop PC. The desktop is slow and sluggish because it's not properly hw accelerated. You can't use it for web browsing because all the modern web sites are too heavy. The low-cost ARM system on chips can run Android fluently only because so much effort has been put into making Android run on them. This work is done by the SoC vendors and is generally not upstreamed.