There already was a huge trend toward niche social media, around the time FB was made. Stuff like Path, Diaspora, Bandcamp, and Yo. They were either cloned and destroyed by bigger social sites or they couldn't find enough traction in their niche.
It's true the techies who lament the decline of corner stores are now more excited about things like Kagi and I'm pretty sure a lot of their marketing is exploiting those feelings on niche sites like HN.
But really, how long have they even been alive? Path tried their best for years and then failed. I hope that maybe enough has changed that folks like Kagi can now survive since wishing ill on something being built isn't my way.