I am not the author of this article but I do have a main account (the one I am replying from) and a faceless one. Yes, you need to pay the $5 for each account if you want to sign up for the Partner Program and get paid from each of them.

I don't know the limit of how many accounts you can have on Stripe. That would be something to look up in their rules. But I don't see why there would be a limit. For Stripe you have to use your real identity and bank account. So, though you get multiple payments from multiple Medium accounts, they would all go to the same bank accoun , unless you have more than one, but even then they are all going to you. You can't be anonymous for the payments due to banking and tax regulations. You can only be anonymous for the writing.