A friend of mine who's lived in South Korea and China for the past ten years tried to open a Monzo account and they denied him without reason. I suspect it's because he hasn't had any credit history in the UK for the past ten years. So suspect lack of credit history is a big factor. Which makes sense, but it does make it useless to a lot of people. Especially given you have to apply to enable the credit features anyway

It helps. No credit history in the UK means you may fail credit checks depending on their criteria.

I would not throw the r word around every time a commercial/credit decision is not what you wished for.