I hate it too but tbf its descriptive of what it originally meant: sticking something into the side of your computer (edit: or any device) and loading software from that.
The term isn't invented by Android and didn't have any negative connotation originally. That's all Android's doing.
edit: what's with the downvotes? I'm stating fact and I'm definitely not defending Android in any way.
edit2: I'm just trying to raise awareness of the history of this and other terms, and how Android and other entities sometimes hijack them for their own purposes.

"sideloading process"
I hate it. It's just setting up software I own on a computer I own. It's literally just "installing".
save