The theme of all of this isn't just to signal. It's that putting yourself out there will cause you to bend and grow. Over and over I read testimonials of people with low confidence who decided to do something like this and found it incredibly fulfilling. Don't just do the things you've always done. Stretch yourself, and you might be amazed what you can accomplish. Blogging improves your writing ability at the very least, and can also cause you to think more critically about your ideas. If you happen to build some influence or good relationships, even better.

Obviously if you aren't interested in any of that, there is nothing wrong with spending the time the way you want to spend it. But it's not about signaling or influence, at least as I interpret it.