Are you joking? I'm 35 and regularly date girls (in SoCal) with an age range of 22 through 28 or so. I have an instagram account which I never use and has about 8 photos on it from years ago. No one ever asks me to show my instagram account and I never mention it. I have tons of "dating success."

So your theory of "social proof" through Instagram doesn't seem valid at all for me. Note: I don't have an active FB account either. So basically, I manage to successfully date many 20-something women with basically zero social media.