Earlier quoted context omitted.
I also hadn't thought about it before, but when you present it that way it's dazzlingly clear - thank you! Get money from your users: 25% platform tax Get money from advertisers: No platform tax
More like: - Get money through the platforms' users and their payment methods, without having to worry about asking for users' credit card information, billing, chargebacks, or individual invoicing: 25% platform tax. - Get money through your own means, similarly to what Amazon did with Kindle books: no platform tax.
You refund 100% but Apple and Google keep their share.