How is telephone calls a solution? Scalpers can easily outsource it to some call center abroad (which they already do for all other types of scams), while legitimate customers now have it much harder.
If the restaurant takes a name and checks on arrival, a third party can not reserve in advance and resell.
Sure, but what does the telephone add here?
It adds friction
The person you replied to is just suggesting that restaurants often don't take your card over the phone, bypassing the opportunity for them to charge you a cancel fee.
Vs. using their online booking platform to do it