I don't know why anyone would think that Apple would make a web page search engine like Google. Apple has already launched the Apple version in your phones integrated into the software you use.
I don't use Siri or any assistant, so I don't seem to use what I'm being averaged into using. Majority opinion here is that Siri is seriously lacking behind the other offerings. Apple won't be oblivious to this. If it is solely due to their back-end search engine, then making that a public search engine website won't do Apple any favors if the results are truly that bad.
Yes I realize that the App Store has ads and it is a stain that should not have ever happened.
Apple isn't an ad-supported business. It's not going to look like Google. It looks the way it's already released.
That they use their own search for this is not a big headlining marketing feature so they aren’t really evaluated on it.
I do think that’s a direct consequence of their experience with Maps, though I guess their hand was more forced on Maps and they had to tell the world about it.
However, using Siri and search suggestion they can, bit by bit, replace search results from other sources with their own without telling anyone about it. It’s a more careful approach.