It’s been answered time over in other threads, but just a couple of examples…
Wanting to keep bills separate, paid other then monthly (4 weekly, fortnightly), not having to force all your finances together, the need for a second debit card (cont-auth payments). Let alone having to wait months on end for pots to be developed to do something that could be resolved instantly by allowing them.
Totally understand some people might be happy with one account and thats fine. But some people need more. There’s a reason every other bank offers second accounts - and its because people want/need/use them.
At least 75% of monzo cc users aren’t using pots. At leat 1 in 4 in the UK (a much larger sample) have a second account.