The idea is it’s more personable, instead of subbing to a Patreon or doing a one-time PayPal or what have you, you “buy them a coffee” or “buy them a pencil” or some other low-cost item that most people both understand helps people AND are cheap/something they might get themselves, so they’re more likely to donate
Also I’m p sure Ko-Fi has a better revenue split with those who use it than Patreon does