The "security" part is of course complete bullshit. They slowly want to turn macOS into a walled garden for more control and profit like they did in the mobile space.
Except of course it isn't complete bullshit. It's saved me a few times where naive family members (one greater than the age of 80, the other under 12) has inadvertently downloaded mal/annoyanceware and tried to install it.
Crapware is a substantial cause of 'my machine's not working properly' among the less technically savvy
I don't know about everyone else but the only reason I even have macOS computers is because I'm making apps for iOS. If it were possible to develop for iOS on Windows 10 or Linux I would do that in a heartbeat.
I don't know much about it but I thought you could develop for iOS using C# using Visual Studio 2017/2019 and it remotely deploy to Mac?
I read a bit about it because I wanted to do it myself but I haven't upgraded from Sierra yet due to no support/broken for my audio hardware in newer versions.