Ask HN: Will this be the end of Airbnb?

I think the argument is that Airbnb and similar take those apartments from the long-term rental market and put them on the (very) short-term rental market, aka the hotels'.

The problem put forward by those arguing against Airbnb is that this is a zero-sum game. If you have tourists who are able and willing to pay more for a flat (aka "middle or higher class"), this reduces housing availability for "the lower classes".

You could, of course, argue that this would be true even without Airbnb if enough "higher class" people wanted to live in a given city all of a sudden. I suppose that's why people also tend to be against gentrification.

Only in the areas that are popular tourist destinations. I guess that's something that NIMBYs seem to care about that I don't identify with at all. Why does it matter if poor people can afford to live in the hottest tourist areas? As we can very clearly tell from the price signals, being there doesn't benefit them nearly as much as it benefits the tourists.

As you say, the same thing applies to the long-term housing market. The price signals are telling us that there's a large social benefit to having higher-productivity workers living in urban zones, and there's an opportunity cost associated with displacing (counterfactual) high-productivity workers with low-productivity workers.