Propery taxes are the same in NH whether someone lives there full time or not, so it doesn’t matter that they aren’t there and would be equally valuable if they did live full time. The traffic argument is the only one I can see being true, except that traffic in the seacoast is awful already anyway with tourists driving back and forth to Maine.
Personally, I think having permanent residents is far better for a town than a graveyard of empty soulless homes, but I’m just a regular human being and I’m sure its just a matter of opinion at that point.