#explore on Mastodon is a good way to find stuff you wouldn’t see on your own feed. (It’s how I found this article.)
And there are various bots that allow you to follow people on Twitter (birdsite.makeup etc). Although my instance has decided they don’t like that so it’s a bit harder to find them than it was.
But yes, I think the article does a good job of articulating the problems. I hope they get solved because there’s a lot I like very much about Mastodon but it does not have the depth and breadth of content (yet). And hashtags do not work well enough as a replacement for search (I followed #BBC to get more news in my feed and ended up with a bit of news and a lot of porn).