I had a friend working with a well known startup founder. The founder was interested in me from what my friend told him, all he wanted to see was my github profile. All of my github projects are private. That was the end of that, even after he already knew that my experience was perfect for their company. So ya, some people definitely put too much emphasis on the github profile.
If you were to share your current job's private repos with me, I wouldn't hire you since that's a signal that you would do the exact same when you leave my company.
this is a perfectly reasonable decision when hiring for a startup, why waste hours, that you don't have, on interviews testing the candidate when you can lookup their past work
Considering how important networking is to startup businesses, you'd think a startup founder would put a little more weight on an employee referral than only considering their GitHub profile.