This isn't a hurdle because people typically aren't going to the fediverse with the idea of "I want a single app for all my social media." That's not how social media works outside the fediverse, so it's not really going to be a surprise that the Twitter replacement is a Twitter replacement and not one for 5 other platforms. If someone really wants to view Reddit-style threads, they're straight up better of making an account on a different platform (just like they would make a different account for Reddit) because Mastodon is a microblogging site.