Re: More importantly: is speed what really matters?
This seems to make 3 assumptions:
First that Safari is the greatest rendering engine in terms of safety, better than anything else that could be deployed on iOS. What makes anyone think so, other than MS acting as an anti-expert of sorts here? I happen to think glitches and JS and CSS standards non-compliance are an indicator of browser immaturity, unless those bits of the standards themselves are security-risky.
Second that I would use Edge. Or Chrome. Most certainly not. Firefox with its own rendering backend is what I’d prefer. Once it had proven robust - see next point.
Third, that I would not privilege safety. I would, but I’d much rather base my choices in that regard on industry experts’ say-so (hint: not MS) than a blanket fiat Apple nyet that ensures they don’t really have competition to challenge them.
Last, iOS itself is pretty robust safety wise. Any _actual_, _demonstrated_, risk to the OS itself should indeed result in a browser’s ban.