The biggest problem with early startups is finding retention: Finding a niche that will stick and continue to use your product.
Most of the projects on Show HN don't have retention figured out, so most of the traffic from Show HN will not convert into useful numbers for them.
I also want to point out that many Show HN projects wrongly assume that HN is the niche for them, simply because they themself are a "hacker". But this is not a useful distinction. If you're looking for your niche, for product market fit, you want to slice into small concrete audiences, like maybe "developers at 10-50 employee startups in credit building fintech within the bay area". Posting a Show HN isn't a cure to not having a niche of users, unless you're specifically targeting this niche.
Most of the projects on Show HN don't have retention figured out, so most of the traffic from Show HN will not convert into useful numbers for them.
I also want to point out that many Show HN projects wrongly assume that HN is the niche for them, simply because they themself are a "hacker". But this is not a useful distinction. If you're looking for your niche, for product market fit, you want to slice into small concrete audiences, like maybe "developers at 10-50 employee startups in credit building fintech within the bay area". Posting a Show HN isn't a cure to not having a niche of users, unless you're specifically targeting this niche.