Because, perhaps, the main one of those "other browsers" is widely considered to be a surveillance tool first, browser second, for a surveillance company and one of Apple's main current marketing thrusts is "we help you avoid people spying on you on your phone"?
This argument falls over when the most popular apps on their store are YouTube, Google Maps, Instagram and TikTok.
They’re fine with “surveillance tools” if they get a cut.
Unless you consider the minimal $100 / year that Google has to pay to be "a cut".
Definitely should be getting a cut of the ads too.
...yes? Who are people going to complain to when ANOther browser leaks their PII from an iPhone? Who will get the bad PR? It won't be ANOther browser because lord knows they've been getting away with it for years with little to no consequence. Why would Apple put themselves - and their customers given their marketing claims to care about their privacy - in a position where that privacy can a) be compromised and b) reflect badly on Apple?