For the vast majority of people, the mobile bank app is far more useful than a desktop oriented web bank. Many (maybe most by now) don't even own a computer.
One interesting usage I've seen is especially younger people, who have a debit card which doesn't allow an overdraft. They then keep their account at or around zero and only transfer the amount they need to the card account before every purchase. That usage is supported way better than my attempts at managing saving, paying large bills or keeping track subscriptions and other spending for the past week.
Most people have at least two. One of their incoming paycheck and one for their debit card. Most have more.
I also have a separate savings account, and one for my cottage, both which get scheduled transfers from my "main" account.
When my debit account is low I transfer $100 or so. Allows me to have a sense of spending that cash gave me.
There's an accessibility element here as well. It's not possible for everyone to use a touch screen.