The problem with this statement is that you're acting like everyone and their mother has a GitHub profile to begin with, and then that they've invariably got a "custom framework" there as well.

None of this meshes with any reality I'm aware of. I'm willing to be wrong here, but considering the statistics I know about hiring, GitHub recreational usage among the average software dev, and... I dunno, my own proclivity to write frameworks, your story is pretty far from believable.

Can you though? There's likely a correlation between the codebase size and how experienced people work on it. If you have a beginner, they're both unlikely to work on a large project and unlikely to create their own framework. And to connect the last bit - the larger project becomes, the more likely it is you'll find some bloat in it. So the custom-framework : bloated-codebase relation becomes a bit of self fulfilling prophecy.