That term at least has a history behind it, as many featurephones had their OS on a small XIP NOR flash ROM, and now the OS is usually (mostly) read-only.

But "sideloading" is definitely a new term of anti-freedom hostility.

I expected someone to say this. In my opinion if there's some history behind something stupid it doesn't make it not stupid

Btw interesting stats here https://trends.google.com/trends/explore?date=all&q=%2Fm%2F0...