These are both good ideas.
If you are a Monzo user then when you click on a Monzo.me link it should open the Monzo app so that you can pay the person using the in-app user to user transfer feature instead…
Obviously that does beg the question, why can’t you do this -
Technically I’m sure that’s possible (even if it’s a little risky as you might mistype the username, especially with autocomplete 
). But my guess is that Monzo won’t want to enable this, bearing in mind that I have been wrong about this before.
Monzo.me costs Monzo money when you use it whereas the in-app transfers don’t. That’s not your problem. But hopefully you don’t mind the friction of adding someone as a contact, in order to make the transfer, rather than having Monzo pay a fee so that you can send the money by username 