On Android distros

I think it's not about "need" - it's a tradeoff between security and compatibility. There's no practical way to do this kind of integrity verification on PCs, and blocking access from all PCs would drive away too many customers, so the banks will put up with a certain level of fraud from keylogging malware etc. But there is a practical way to do it on modern phones, and blocking access from unverified phones would only drive away a small number of customers, so they've decided the reduction in fraud makes that worthwhile.

(My bank also makes the app much more convenient than the website - e.g. I can set up new payments through the app with just a fingerprint (and maybe facial recognition if it's a large amount of money), whereas on the website I need to type in my ID and password and then insert my physical card into a card reader to generate authorisation codes to type in. There's always a security vs convenience tradeoff, but the improved security of the phone platform means they can increase convenience and still keep fraud within acceptable levels.)