It is not a conspiracy. Just like the iOS App Store it is for your own protection. There is no legitimate reason to run your own software on general purpose computing hardware.
I really hope no one would ever think this non sarcastically.
Security is about tradeoffs, most notably security vs convenience, but also many others.
Anyone who suggests that their personal preferences in tradeoffs are not just universally correct but also the only reasonable position to hold is just silly.
Oh no! That will never happen. Because it runs on Apple M1 kryptonite chip that even Superman can't touch. /s
For most people there are, in fact, no legitimate reasons to run "their own" software on "general purpose" (read: household appliance) computing hardware. Almost nobody runs custom software on their washing machine or toaster.