Earlier quoted context omitted.
You can get a developer account, build and sign your own executables, and run whatever you want on your iPhone. I don’t think those flashed ROMs give you appreciably more “control” over your iPhone than stock iOS provides, because actual control requires usable control surfaces . More likely, you are replacing the control surfaces provided by an accountable entity (Apple) who has prioritized your security and privacy…
The iOS feature set is intended to protect Apple's business model and revenue streams by forcing you to do things in Apple's jail. Getting a developer account is obviously an absurd and impractical approach to distribute software and proposing this is frankly ridiculous. It's not free, requires you own a Mac, and is way beyond the technical abilities of most users.
I mostly agree with you, but you don't necessarily need a Mac in order to use your developer account for sideloading—you can also use Cydia Impactor which is available for Windows/Linux.