As far as laws and restrictions are concerned, I agree that the free market should continue to be free, but we will always need laws. And those laws are impacted by what society deems as moral. I would not be in favor of a law that dictates how many homes you can buy, or who can and cannot buy, but even current tax laws provide incentives and disincentives for various actions, in the housing market and also the stock market.
For example, even if you sell your primary residence before two years are up you can still claim a partial tax break if you had a death in the family, lost a job etc. If you don’t meet the criteria, you get no breaks. These laws are in place because as a society we have decided that it’s beneficial to give tax breaks to encourage home ownership, but also to encourage people to keep the home at least two years to provide some stability to the market. Builders and communities are also crafting rules against flipping because they have realized that flipping can have a negative impact on business and neighborhoods.
Arguments I’ve see about the morality of this center more on the disruption and instability to neighborhoods it causes and not necessarily on the fact that a family now has to pay more for housing. And most of my beefs with the current system have to do with non-independant insiders gaming the system without consequence. Buyers also need to be held accountable to know that flipping is going on and to stay away from those areas, just like they should be expected to know that a 1 month interest only loan might be a bad idea.