If I had to guess, it would be Gatekeeper and SIP. These technologies can really get in your way if you’re used to having full access to your own machine.
It’s just that I still need macOS for iOS dev right now, but that might change in coming months ...
Personally I leave both on because even having used computer for 27 years at this point, I can still slip up and I’m still vulnerable to social engineering among other things, and so it’s nice to have something to help cover for those situations. It’s no cure-all, but it at least raises the bar for malware and such.