There's this really cool site where you can see how well supported a feature is: https://caniuse.com/?search=if

If Google controls everything, why is if() only supported on 59% traffic? Do you think any serious company will let their site break on 40% of clients? Do you think Apple's opinion is unimportant?

Did you look at detailed usage stats? More specifically at things that do not count towards that 59%: older versions of Chrome add another 20%, various Chromium forks add a few percent more, so the rest of the internet accounts for less than 20%. I'd say this is pretty monopolistic for one company to control the means of more than 80% of traffic of doing its 'trafficking'.