I think the argument being made is that these individuals are creating scarcity as a byproduct of their intended goal, not as a goal in itself. If they wanted to profit from the scarcity they induced, they would attempt to resell the items they bought in the original locales rather than at online venues.
Not everyone is scalping, but everyone is buying more for themselves because they're suddenly worried about future supply. There would still be a temporary shortage without the scalpers, maybe slightly less severe.
How much TP do people really need for themselves? Why are the shelves cleared out of TP and not, I don't know, dish detergent? Why is its future supply more in danger than any other good? If everyone coordinated buying a month's supply of TP one weekend, would all the stores really run out? I'm not so sure... At Costco it's hard to buy less than one month's supply at a time already, unless you have a big family
If a pack of TP lasted as long as a jug of dish detergent, it wouldn't fit in a car trunk. In volume/day TP is second only to water and food and much higher than any other staples.
If a million people normally buy one pack per month spread out evenly on weekends, but all of them think hey, maybe it's a good idea to get two packs this weekend, that's 2M packs where they had stocked for typical sales of 1M / (52 / 12) = 230K.
