Indeed. I switched from macOS to Windows about a year ago now and I have to say I really appreciate how on Windows stealing focus is much, much more rare than it was on macOS.
I know right? Especially when you've just booted up and half your apps are still realising they've just been opened and screaming for attention. They should just open in the background and only appear when I look for them. I don't understand why they haven't tackled that in 18 macOS versions. Simply launching an app with a flag saying "this is not a user-initiated launch but a reopen, stay back" would fix it.
At least bootup is a lot quicker on the latest M1s (privately I use KDE now but for work iIm still on Mac)
Apps used to open in the background in macOS. Also OS dialogs would not steal focus iirc, or maybe those modal dialogs dood not exist. Not stealing focus used to be one of the top rules in the Apple human interface guidelines.