It’s all about trust. The problem is that people trust Apple not to steal your credit card information and to honor subscription rules etc. You probably trust the independent platform a bit less, such as many of those scammer platforms who might even charge people more than they should by “mistake”, then have an awful process to get reimbursed etc.
In that sense, most people will always prefer Apple to manage these things. Everything’s then in one place, and you trust that once you cancel it you won’t be charged again.
As an example, I had a Netflix subscription and after I cancelled it, I’ve got 2 or three emails saying “Thank you for reactivating your subscription” which I didn’t do. I suspect they make some pop up that my mom tapped without noticing, but that definitely shouldn’t happen without my password. I could only solve the problem by adding a second payment method (which doesn’t work) and only then it allowed me to delete my previous credit card data.