Whether or not you want to call it 'significant', every $15 meal they sell for $8 is either $15 or $8 in revenue that a legitimate business didn't get.
This phenomenon literally breaks capitalism, by routing money from those who can create a product for that price to those who are subsidized, because they're 'innovative' enough to make a cookie cutter mobile app and wear skinny jeans with fashionable glasses.
Now, a standardized delivery model, with a straightforward service charge, and all that? Yeah, great business model. Seamless web is around. They're doing great, and add value to the economy. What value do these clowns add?
You don't seem to disagree with any of this.. your position is that since they'll be out of business soon, the damage is limited? It's still damage, and still stupid.