The "biggest hurdle to conversion is friction in the purchasing process". We're talking about the "enter credit card details" stage here. Which is hardly the "biggest hurdle to conversion" -- it's where conversion has mostly already been made.

You first need (a) a decent product, (b) to present it nicely on the web page, (c) good copy, (d) appropritate calls to action, (e) a pricing strategy, (f) to get the customer to decide to buy. Only then the "friction in the purchasing process" (with respect to entering credit card details) comes into play. At the very last stage of conversion.

But that's beside the point.

In my question I didn't specifically doubt that the "biggest hurdle to conversion is friction in the purchasing process".

I merely asked the parent to qualify why he thinks this specific form will "stop people for paying".