> You can do it once, and save in in your bank app.

I try not to send or write my IBAN just anywhere. With things like Direct Debit, I treat it with care. Sharp contrast with Paypal, where you can use your email address or even have a paypal.me page that does not expose your email at all.

> Isn't instant SEPA required to be supported by all banks now?

Yes, and yet I think it's not supported by all banks. Especially those that are not in the Euro area. One more thing - many people including me are to this day not informed or aware if instant payments are charged by banks or not. I honestly don't know.

Good point about Direct Debit, thank you.