We have a lot of users who care about groups, the basic groups for organizing playlists are free, if you want extended features you should become a patrons. We're showing Patreon screen on every of our videos. It takes time to update the extension every time YouTube changes internally.
Furthermore, the decision to keep some features for the Patreon version of PocketTube was made to ensure the long-term feasibility of the free version.
Edit: I understand you don't care about my hard work around the extension, we all like free stuff. But in a world where everything is free, we are the product.
Edit2: Ok, added it to a description