Tell me if I'm wrong, but you only pay once for these titles, no? Early access or not, they charge their players once and any updates released after that are free unless they can sell them as some kind of DLC/Expansion. That's atleast how it works for regular games.
That's why developers like DPC release their games in Seasons, otherwise subscribing to Patreon would be pretty much pointless if one can just do a one-time payment on Steam instead and receive new releases for free. You know, like patches for regular games.