In essence, while the app stores used to be about hobbyist software to some degree, they have become a place created by big companies for big companies, much like Walmart or Target. That would be fine if customers could choose when they visited Walmart or Target, but instead, we've created a regime where you must buy everything from Walmart or Target.
This has made mobile development a wasteland for hobbyist-built and community-built software. I know some people cheer this as the removal of amateurs and crappy software from the marketplaces, but I would counter with the observation that commercial software often doesn't have my best interests at heart, and I would, many times, prefer a piece of community-built or amateur software instead. This gets harder to procure with each passing day.
So, I think developers are generally better-served leaving mobile development and instead focusing on web development, which is not gated in the same ways. While you won't have the same reach that you would get through the app stores, you do have much more control over the platform on which you're developing.