NEW YORK (MainStreet) — The accusation is blunt: Airbnb, say some, is sucking up apartment units that otherwise would be available to renters. In San Francisco, that claim is spoken so loudly - by so many politicians - a city agency just filed a report on it.

Similar claims are heard in Santa Monica, Calif., in Manhattan and some Brooklyn neighborhoods, a few areas in Seattle and also a sliver of Boston and adjacent Cambridge. True? False? Is that Airbnb host putting vacationers up in what should be your prime Greenwich Village flat?

Some think such accusations are just distracting from the main issue at hand: housing inventory shortages.

“It’s a diversion," says Richard Green, the Lusk Chair in Real Estate at the University of Southern California. "Politicians are not dealing with what they should be dealing with to address housing unavailability so they are singling out Airbnb.” His nuanced point is that in most markets the number of Airbnb units is trivial and so whatever impact it has on apartment availability is minimal.

The San Francisco government report does not disagree: “the Budget and Legislative Analyst estimates that between 925 and 1,960 units citywide have been removed from the housing market from just Airbnb listings. At between 0.4 and 0.8%, this number of units is a small percentage of the 244,012 housing units that comprised the rental market in 2013.”

Read the San Francisco report. It said that under 1% of apartments have been removed from rental channels due to Airbnb. How important is that? What does it mean?

What is unique about San Francisco - also Manhattan and a few other places - is that apartment vacancy rates are fiercely low. In a recent survey, it stood at 4.1% in San Francisco and that means this is the type of town where would-be renters get in line early whenever a decent unit goes up for rent. Add back in those Airbnb units and, yes, that might be a happy day for some tenants. But not many.

The other unique feature: San Francisco, Manhattan and a very few other places attract large tourist populations, especially Millennials, and that has been a sweet spot for sharing economy rentals. Take tight supply, add in high hotel prices and a flood of tourists and there is the recipe for cries about any apartment that seems to be lost to the longterm tenant market.

In a lot of markets - from Phoenix to Houston - vacancy rates are already high, tourist numbers are low and nobody really thinks Airbnb is having any impact on local rentals.

But in some cities it just may be. Harry Campbell, TheRideShareGuy.com, said of Airbnb: it is “having a huge impact in coastal communities [of Los Angeles] like Venice/Santa Monica where mid level chain hotels can run upwards of $300-$400 a night. It just doesn't make much sense for landlords to rent their apartments out traditionally when the profits are so much higher using Airbnb.” (Santa Monica, in mid May, enacted legislation banning short-term rentals such as Airbnb. Nobody knows how it will be enforced or if it will withstand legal challenges.)

At least one Portland, Ore. Airbnb host emailed Mainstreet to admit that two apartment units that had been rented to regular tenants are no longer. Explained that host: “From the point of view of a former landlord, the Airbnb experience is far superior. Airbnb guests are, on the whole, responsible, considerate and never late with rent since this is collected in advance by Airbnb.”

Either way, however, the calculus is not one-sided, not even in those premium markets like San Francisco. Green added: “You could also say that Airbnb is increasing the stock of affordable housing units by letting some keep their apartments by occasionally renting them out. It’s entirely possible Airbnb produces as many units as it loses.”

In that regard, listen to Kip (last name withheld) -- a self-described 60+ woman living alone in Beverly Hills in a two bedroom apartment. A few times a month, said Kip, she rents it out through Airbnb. “That helps me with the cost of living,” she said. She stressed she would never take in a roommate but is happy with having guests a few nights a month. “It’s helped me boost my flagging income,” she said. 

Christopher Nulty, an Airbnb spokesperson, had fighting words in response to the San Francisco report in particular.

“This comes from the same people who want to ban new housing in the Mission [a San Francisco neighborhood], ban home sharing and make San Francisco more expensive for middle class families," he said. "Home sharing is an economic lifeline for thousands of San Franciscans who depend on the extra income to stay in their homes.”

So, who’s telling the truth?

“When evaluating claims about Airbnb, it is important to keep in mind whose ox is being gored,” said David Reiss, a professor at Brooklyn Law School. His point: In some cases, maybe Airbnb brings some harm. In other cases, it does good. Matters just aren’t simple or black and white.

But, said USC’s Green, the solution to housing unavailability and unaffordability in San Francisco, isn’t to ban Airbnb - “Airbnb is a pimple,” said Green. The solution, he said, is to build more housing - but that does not appear to be the answer at least some pols want to hear.

Written by Robert McGarvey for MainStreet

This article is commentary by an independent contributor. At the time of publication, the author held TK positions in the stocks mentioned.