Why? A blog is a very different use-case than social media (even social media based on microblogging). Yes, many social media communities are toxic, but many of them (or at least parts of them) can be incredibly enriching. There are plenty of Mastadon communities run with open governance structures.

Besides, most presenters will also list their personal URLs if they have sites they'd like to promote.

yeah... ideally, there should be a reachable identity system for everyone, independent to centralized database. Content can be anywhere, RSS is nice, a content authentication system is nice too, but what's missing is an identity system.

Maintaining your own site instead of using a common, sensible, resilient solution might be antithetical to some notions of being an SRE. A personal blog is also not a replacement for social media. Hacker News is something that an individual would be hard-pressed to replicate on their own.