I understand where you're coming from, but if they weren't interested in having non-premium content, they could simply have opened submissions for premium content during the month of July instead of making a contest for non-premium users to post on the site.
Let's be realistic here for a second though, of course Tapas would want to get more premium content, because premium content is what's keeping the site alive. It takes a lot of money to publish a series/pay editors etc. and without revenue I don't see how it would be possible to keep going. (Not to mention paying for hosting etc.)
I personally am thankful for all that they are doing and trying to do. So far out of all the writing sites I've tried, they definitely offer the most exposure (imo) for new creators and non-premium creators. The staff picks are often non-premium creators, as are the daily-snacks. The front page spotlights are also shared between non-premium and premium creators. And I've yet to participate, but I've heard tipping events are great, and also not premium exclusive. I'm sure I've left some stuff out, but you get the idea.
Sure, not everything is perfect, just like on other websites where you will always find positives and negatives, but I feel like there have been a lot of complaints about Tapas lately without people looking at the bigger picture. Tapas gives attention to both non-premium and premium creators, not only that, but they are very accepting of diverse comics and stories that would get censored/banned on other sites (e.g just for being LGBTQ+ for example like what recently happened with Youtube).
You can tell Tapas are trying hard to make this website/app great as they listen to suggestions from users. I don't know many websites that care this much about their creators. Even if certain suggestions haven't yet been put into place, they are a small team (as they have revealed in a newsfeed post recently), and this stuff takes time. Imagine trying to balance your livelihood (premium content) and giving attention to independant creators all the same; it's difficult stuff, and I can understand why it'd take some experimentation to find a good formula that works.
I'm not currently a premium creator, so I get where you're coming from, but Tapas have already made a pretty great platform so far and I trust they will make it even better as time goes on. We should be looking at the bigger picture and giving them our support instead of being negative about this, if something displeases you, remember that there is a suggestion thread where they are willing to listen.
Sorry this turned into an essay, I just feel like there's been a lot of posts about how 'bad' Tapas is doing lately, and I wanted to bring a different view into perspective because to me they've just been a really great site that I don't believe deserve all this backlash. 