The purpose of Patreon for most artists is not to make it their primary hosting service, but to make it a "bonus" area for those who are willing to pay for said bonuses.
For example, an artist might post a new strip once a week. But for people who pledge $3/month on their Patreon, they might get a bonus strip each week (at two strips a week). And then at whatever increment they choose, they could also give away wallpapers, concept art, mini strips, first dibs on request drawings in livestreams, merchandise, etc.
Most artists don't make Patreon their primary hosting service only for those who pledge, because that can seriously hurt viewing numbers. Yeah, it's nice to get money when that one person does pledge, but most people won't pledge for something unless they already know what they're getting and know that they'll enjoy it.