I would like to ping this. It's really too bad this is still not implemented.
It's a naturalized gesture with mobile users. Ever person I have seen using my website tries for this and then it's an awkward explanation of why it still can't happen. It's like a piece of software that hasn't upgraded to the mouse but uses a GUI.
It's a huge missing step and I would be open to seeing how we can crowd-fix this or submit this to the Squarespace team so they can implement it. It's not rocket-science or a neural network for hashtags. It's pinch-zoom!