> Question: if there's no website, how TF are you supposed to use Monzo or Revolut from a proper computer?
You can't. That's why you don't use them for serious work.
> why did you even open an account
Different use cases, different circumstances. I don't depend on them but they give good exchange rates and zero fees when transferring or spending money abroad. It's the "it just works" and "fast and cheap" effect that the traditional banks don't have. And opening an account is done online, and you get access to your account in hours, compared to Barclays which took 2 months of ping pong, when I first moved into the UK (since I did not have a bill issued in my name at my UK address I could not open an account, so I could not pay my landlord rent so I could get an address to open an account, fun times). Without that Monzo account I could have not been paid in my first 2 months.
But if you want to know how crap Revolut really is, try contacting their support to report a bug in their app, they don't have an email, but instead ask you to get in touch with them on Facebook.