There might have been an after-market for these reservations where you could buy one if you want to. But now what? I guess it's just a race to call the restaurant? Or to reload their reservations page over and over again on the day they open them for the day you want? If I want to eat a Fancy Restaurant, but they are normally fully booked - what do I do now?
The folks that resell reservations like this are addressing an actual problem in the market. Perhaps you do not like that they are earning money doing so, but preventing it doesn't fix the problem either.