Yes, discovery is a big problem these days.
With all the new media and publishing tools we have now, and so many people using them, there's just too much creative content being released - books, games, music, videos - such that matching up potential customers with products they might enjoy has become an unsolved problem. In video games, for example, on the Apple app store or the Steam store for PC games, there are now hundreds and sometimes even thousands of new products released
every day. Titles that have the most marketing grunt behind them will rise to the top of the "new releases" charts, and the vast majority of people browsing will generally never click past the first page of search results. This means that large numbers of less well recognised products - some of them even of high quality and potentially just what the customer is looking for - will sink into the morass of obscurity very quickly, and that's also why every time you look at the "top selling" app or book lists you keep seeing the same big-name titles week after week, with only the occasional blip of an indie title that might have gone viral for some reason. Publishers often spend thousands or even millions on tuning their ads and search engine optimisation (basically, keywords and priority bumps) to force their product to show up in that first page of results on the various stores, and while the stores make the right noises about trying to improve discovery for the little guys, they are quite understandably unwilling to change this very lucrative process that favours the publishers with deep pockets.
I don't have any stats for KDP and other ebook marketplaces that allow self pub, but I'd imagine they are at similar levels of saturation and reliance on marketing muscle. It's all dirtier than a fifth ace, but I don't think anything is going to change any time soon. The best approach for a small self pub author without a traditional publisher behind you to take care of all this marketing stuff, in my opinion is to build grassroots popularity among friends, internet presence on forums and social media, and so on, and hope that enough interest from those quarters will cause the store algorithms to move you up into a position on the search results where you might have a chance to go viral. There's no easy answers, really, unless you have a billionaire uncle with strong marketing contacts.

"I've stopped giving advice. Even when people ask for it, they resent getting it." -Ross Macdonald.
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