I'm not sure that an Apple targeted ad platform would be seen as very different from Facebook's targeted ad platform by consumers. It's true that Apple have a better track record of keeping data private, and there's been no Cambridge Analytics style atrocities. But providing tracking ads of any kind (whether bundled by cohorts or what ever privacy enabling methodology could be added) could tarnish their reputation.
Just because a business can destroy another huge companies business model it doesn't mean that replicating it is a good idea.
Just because a business can destroy another huge companies business model it doesn't mean that replicating it is a good idea.