That's simply not true.
Itch has up to version 11.1. As with pretty much everything, Patreon subscribers get early access to new content to reward them for their ongoing support. People who buy the game via Itch will get the latest content some time (weeks? Months?) after the Patreon supporters.
Think about it this way - One payment (Itch) vs. Monthly payments (Pateron)...who do you think is going to get the goodies first?