Sure Patreon raised funds, but those funds can't subsidize them for a lifetime, they gotta get sustainable and do it fast. There is not a chance they will be wasting time to build their own credit-card processing, so Stripe fees are here to stay.
Although contributors are important, Patreon would have nothing without their creators. Creators make the content which people pay for, and creators need to put food on the table to keep doing what they are doing.
If you are a creator making $2,000 a month, for example, then an extra $100 is an extra trip to the grocery store, and that's important. If someone wants to fund a creator, they will, and the extra couple of bucks isn't going to discourage that.
Furthermore, I suspect Patreon has data on how much is being contributed by each user. I doubt, like the top comment suggest, that 1 person on the platform would fund 100 creatives. Probably 1:3 ratio, with a couple of outliers, is most likely.
This is a good change.
p.s. If they don't have it yet, expect Patreon to start partnering with places like Teespring to offer merch by their creators. It just makes sense.