You claim they only do it protect the App Store monopoly… so if users will just download something else, what would be the point? The things you want them to add (what you claim makes them uncompetitive to Chrome) completely defeats the alleged purpose of supporting their own engine. So why would they pay engineers to work on that? It’s nonsensical, magical thinking.
I seriously hope you will reflect on the real negative consequences of what you are doing to the web. This isn’t one of those times when you can just stick your head in the sand and repeat the mantra “I’m just typing code”.
Once Safari is killed, Google can really start ramping up the war on Firefox because the collective market share of non-Chrome browsers will be too small to matter. You are killing the open web that you claim you want.