That's a bad analogy. If receiving bitcoin payments required people to post their private keys...
Then you don't understand the analogy. It's about misleading people to do something that you know is unwise.
But (and this is a separate point, you keep introducing separate points ala the
Gish Gallop) it's true you can't make a non-XRP payment to someone unless they have indicated someone they trust to hold the funds. Just like I can't wire transfer someone money without knowing what bank they trust to receive the funds.