There's a saying that goes: "God helps those who help themselves", which I don't always agree with because it tends to get thrown around by libertarians and people who disagree with free healthcare, but I think in this case, it's relevant.
Tapas has no responsibility to promote your comic. Even if you're a really nice person, even if you regularly post on the forum, even if you pay for premium content. Platforms are not your friends. From their perspective, promoting a comic that isn't premium is really only worth it if it has at least already managed to hit that 100 sub target and enabled ads. More views = more ad revenue = mutual benefit.
They're giving me free hosting with a reasonably short URL. They're giving me the chance to be seen in a list of comics. To me, that's an okay deal, even without the chance to be featured. And they let me keep all the IP to my comic. Is it weighted in their favour? OF COURSE IT IS, they're the ones paying for everything! If I don't like it, I'll have to peddle my comics elsewhere, like pay for hosting and build a wordpress site like I had back in the day and take visibility into my own hands. In my case, I've looked at my options and decided "this one works for me", but Tapas is no more my friend than my bank is. It's a business, they're offering me a deal and I'm okay with the terms compared to the other options.
Whether or not Tapas features you, the biggest factor in your comic's popularity is YOU. It's painful to hear, but it's true. If you aren't making your best effort to make your comic popular, why should Tapas try to force people to be interested in it? You have to be honest with yourself about whether your comic is a personal piece of art for your own enjoyment or a product you're selling, because saying and acting like it's the former, but expecting a queue of customers anyway isn't realistic. It's a nice daydream to indulge in where I just draw and write whatever I like in whatever format I like without a single artistic compromise to my vision and it gets 10k subs and a feature and then Netflix comes up and is like "Hey Kate, Rebecca Sugar was so impressed by your comic, she wants to head making it into an animated series with animation by Studio Trigger"... That is not going to happen. (Even though I deserve it for being such a flawless human being, obviously.)
Any choices you have made to make your comic less accessible and less relevant to the audience here are your responsibility. You have to own them and be at peace with the fact that yes, if you have made a choice for artistic integrity or indulging your own personal favourite styles or themes rather than catering to what the audience here are into, it's very likely that the audience will not want to look at what you're making.
You made a product that they're not interested in? You didn't market it strongly with an eyecatching thumbnail or a clear description? And you want Tapas to invest space in their shop window as what... a favour? Because you're nice? I've pitched to publishers before and been rejected. I don't then tell those publishers that they ought to publish me because I've always supported their products and been an active part of their fandom. Tapas doesn't owe me a feature any more than Marvel owes me a gig as penciller on Runaways (Marvel did send me a script and have me do pencil samplers for Runaways once. It didn't work out. It sucks... but like... yeah Kris Anka is awesome, I'd be lying if I said I thought I'd have done a better job).
I chose to make a comic in one of the smallest genres on Tapas, to work for print first, to not pace it in the style of a Tapas comic (which is setting up the premise within the first 3 updates) to not make the main character a hot bishounen, and to draw with a style and colour palette that don't fit in... right, I made a bunch of decisions that will negatively impact the popularity of my comic, and I know that, and I take responsibility for that. My plan to get my comic noticed has never factored any expectation of any sort of feature from Tapas, because I know I made these choices, so the responsibility to prove I can engage people despite that and to bring in an audience is on my shoulders.
But even with these barriers, I sailed past 100 subs within 30 pages without doing any "sub for sub" stuff, without needing a feature. I did that by doing my best to market the crap out of what I have with the resources at my disposal. I made sure I had an eyecatching thumbnail, a strong description, very readable pages, a story that keeps supplying action, tension and drama. I give back to the community by giving in-depth critiques that I put a lot of effort into. I have actively made changes to how I describe my comic and the pacing and length of updates based on feedback to make it more appealing to Tapas readers.
I've been a woman in comics long enough to know that life is unfair and I can't rely on companies or publishers to do anything for me. I've always had to build my own audience and make my own doors. A long-shot advantage like asking a company to feature my work for nothing more than charity is low on my list of "viable advantages" and I'm much more likely to use advantages I have actual control over like making changes to my comic, marketing on other sites etc.