First, they have a huge buyer: themselves. This also means they can closely integrate with the AP and driver folks.
Second, Apple is not Intel. Intel is famously quite bad at managing the development of anything that isn’t a CPU. Apple (or, frankly, basically anyone else) may be able to fix the cultural issues that make it impossible for Intel to build a reasonable non-CPU product.
Aren't Intel NICs considered the best, due to the way it manages interrupts (can't remember the source at the moment but I did read somewhere they were better than RealTek but maybe not necessarily Broadcom)?
Also every Intel motherboard of course has an Intel-developed chipset.
Didn't Intel also develop HDCP which is also in every television and graphics card at this point - though I'm not sure what Intel hardware is behind that.
Intel NICs are indeed good. I suppose that an exception. I don’t know much of the history behind HDCP, but the crypto is a joke.
Interesting things to look up: SoFIA, Puma 6, all the Atom-based phones out there, Larrabee / Xeon Phi. A lot of money has been spend, and the returns have been dubious.
Well, in recent years they've managed to develop reasonably decent integrated GPU's that are perfectly adequate for anyone that isn't using graphics programs extensively or more than (very) casual gaming.
I think the issue was more than Intel was running behind on their roadmap, unable to deliver on the promised schedule. This is what drove the Apple-Qualcomm settlement. But that settlement gives Apple years to work with this acquisition to bring it to "good enough". And their experience in chip design thus far has shown they can shepherd chips through design and implementation that are more than just "good enough".