Your github profile is no more or less than an indicator of your activity on github.
The problem is when people take the absence of github activity as absence of activity or experience. It's an intensely narrow view of what "good coders" look like.
Github profiles are misleading for...
From my perspective as a hiring manager, a github profile is a crapshoot. If they have very little activity I pretty much just move on to other sources of info (ie. it doesn't really help or hinder); if they have heaps of activity it creates its own challenges:
You can work it all out but it is really time-consuming to build a good picture of what's actually going on behind that strip of green squares. One thing I can guarantee - hiring managers are time poor (by definition their team needs more people), so if you want the job you really want to make it easier not harder on them.
Unless someone is showing absolutely rockstar levels of gh activity, it's unlikely starting with gh is the most effective way to evaluate them as a candidate.
So when I'm hiring it's not a disadvantage if you don't have a github profile; it's not automatically an advantage to have one; mostly I'm going to use it to work out questions I'm going to ask you when I talk to you.