While that's true for people who have a traditional education from a good university, an established network or live in a tech hub or have the ability to travel

While that's true for people who have a traditional education from a good university, an established network or live in a tech hub or have the ability to travel to one, having an online presence is very helpful as an alternative to real-life networking for people who lack those things. For someone from a developing country, changing careers or looking for remote work, an online presence can provide them with opportunities they would not otherwise be able to get. Of course, that online presence should actually have something substantial and probably shouldn't take the form of yet another basic tutorial blog post. Also, there's no reason why a programmer's online presence should be only about side-projects or programming. Running a website related to one of your other hobbies is a perfectly acceptable way to provide a conversation starter (which is all an online presence is doing most of the time, anyway).