When I was working more frontend (~1,5 years ago) no browser would cause more work and trouble for us than Safari on iOS (we didn't have to support IE9 and lower).
Also I understand that Safari might've created some pain for you as a frontend developer, but frankly I don't care. I'm an end user and I only care about how fast and secure the browser is. And Safari wins there, it's not terrible by any measure for the end user.
Development wise it's not so much about our pain as about certain known bugs that went unfixed for up to 2+ years, similar goes for a range of CVEs (re:being secure).
I realize that this is subjective, but Firefox Focus has been my preferred mobile browser, regardless of if I have Safari available, (iPad), or not, (Android). In fact having desktop addons on Android has been great.