I disagree. I think most people could do just fine without them. Some might need to buy a desktop computer or even visit their bank's website using a browser on their phone, but humanity got along just fine without cell phone banking apps for a very long time. Many of the old options still exist for a lot of common banking activities. Options like calling your bank on the phone, using an ATM, or going to a branch in person. If your bank really doesn't allow you to do anything with your money without a cell phone app I'd say finding a new bank is justified. Better yet, try to find a credit union.
Banking apps are convenient, but it's getting to the point where the inconvenience of being abused by the OS outweighs the convenience of a banking app which is probably collecting (and selling/exploiting) data they couldn't get from a visit to their website anyway.
when desktop browsers are considered less trustworthy to the bank than mobile apps (this is approximately now) they'll invert the functionality and limitations surface so mobile will have more authorizations than desktop browser (this is also happening now).
client attestation is a fundamental transfer of freedom from the client to the server. it's nice in theory (I too want my money safe), but at the very least it needs a third party with different incentives, not the OS, hardware and browser vendor.
The only need I have for banking apps is created by banks themselves, to verify online payments. But it would work just fine with regular text messages. I don't need a banking app at all.
(And maybe verifications aren't needed either, since in the 40+ years I have been using a credit card, never once have I been asked to verify something that I didn't initiate myself.)