This is my take. Most of my (https://rich.sh/blog) blog posts, are of actual things I can screenshot or take a photo of, and if I can I'll use that.

But, for abstract posts, random bits of code, notes, etc - it looks bad to have them be all the same generic icon or my headshot for them it seems off-putting. I'm not a graphic artist, so I instead use MidJourney generated icons for social / post icons that match the topic of the post.