This could be one of the reasons also. Some influencers see multiple contact methods via different channels as stalkerish. In my experience, it's better to follow up on the email, and perhaps one social channel they are active on.

Also, if you used "expert" in the pitch, that could have been a turnoff - I'm currently working on a piece that explains this mindset.

True, though, most influential people are just too busy. But plenty do take peeks at their own accounts.