It doesn't matter as much if an iOS upgrade breaks stuff as a Mac OS upgrade. The iOS market is so strong that developers rush to make their software compatible. Within a month of the iPhone X introduction I had dozens of apps with updated that just said they were updating to support it better.
Mac updates are a lot slower if ever.
Fortunately, the only apps I really care about besides the browser are developer related tools. Those are usually updated relatively fast on Macs and Windows.
iOS 11 didn't break things because of API updates. It literally broke phones. I had three friends switch to Pixel because of iOS 11 bugs, like not being able to make calls. Apple told them all to upgrade to a new iPhone.
If that was a widespread problem. It would have been another "gate". Like "BatteryGate", "AntennaGate", and "Bendgate". There hasn't been a "Bendgate".
There also haven't been widespread reports that Apple told people that couldn't make calls on there phones to buy another phone - if that were true there would be yet another class action suit. The lawyers would have been salivating.
Mac updates are a lot slower if ever.
Fortunately, the only apps I really care about besides the browser are developer related tools. Those are usually updated relatively fast on Macs and Windows.