Depends how much people like to (or need to) reach out. I don't think it's mainly technical. I started late in my profession (land planning / ecology) while most started during uni so grew up with their network so they don't need to develop one - that's part of what I think is going on.

Also I don't see many traditional professionals as wanting to reach out and I find it enjoyable, and remunerative.

I have a wordpress blog (found via bt w3 site) and two twitters so not too walled that helps me reach out and be more findable. Self-hosting would take me too long to read up on as seem to be many options but I suspect most are unfit.