• The ownership stat you point to (7% of owners own 50% of STRs) is likely inaccurate. Transparent probably gets its data from rental listing websites, and not property records (that would be highly difficult, if not impossible with entities like LLCs in play). There are many many companies who operate STRs for owners and therefore list many many properties that they don't own. This is definitely worth looking at more deeply, but I don't think this number is accurate enough to be relevant, although the concept is.
• Many other previously accommodations are now gone. It used to be common for one or more small inn or hotel to operate in every single small town, as well as multiple Bed & Breakfasts, guest houses, etc. Take Burlington for example - think about how many motels there are/were in town and down Shelburne Rd. that are no longer accepting short term guests. Sounds crazy at first, but look at every 20-50 room motel and then consider that the visiting population is growing, and each one of those rooms now becomes an apartment that someone has chosen to rent short term.
• Most Second Homes and STRs were never part of the available housing pool. A [multi] million dollar lake or ski house, or rural retreat/farmhouse/lodge is not suitable for long term rental in a meaningful way. There's no way to take an empty 8 bed, 10 bath luxury home and repurpose it as an affordable rental. Keep in mind that much like our economy, our housing stock is not zero-sum. Someone owning a large second home does not mean that another person doesn't get to have a home - it doesn't take away from anyone else. That house wouldn't have existed without the will and resource of whoever owns it, and they haven't repurposed it from a local person looking for long term housing.* The larger socioeconomic implication probably points at that second home owner taking something from someone to build that house, but more like taking money from local people wherever they made that money...

To beat the obviously dead horse, AirBnBs are taxed same as hotels.

A different approach (consider it before you burn me). 1. Reduce requirements for affordable housing in most of Burlington. 1. Reduce tax on new housing development. 3. Require institutions to sponsor high density housing near their campuses.

What we need is more, better housing stock. Only private enterprise will create this, and only if it's profitable. If developers can make unlimited amounts of new units with incentive to make unlimited profits, they will. Unlike trickle down, this is rising tide - it lifts all ships when more, better housing becomes available. Those who can afford it, do, and leave in their wake vacant "better" housing. The current practice of enforcing affordable housing in all developments only reduces the likelihood of them being built, and doesn't actually create more affordable housing (see: Vermont).

Real capitalism doesn't provide the greatest good in most cases for basic needs, but for housing it actually might - maybe the best waterfront location in all of Burlington should be rented at market rate instead of as affordable housing? For instance, if the building at the end of lake street was rented at market luxury rate it would generate 3-4x (?) revenue which could be used to provide 2-3x the amount affordable housing in another location. This might be an unpopular idea with some folks, but probably provides the most common good.