Not sure why the amen is applicable to Dutch cities. I'll take the local perspective from Amsterdam as an example, but it applies more broadly to the other cities as well here.
Regarding point 1:
There's no real issues with long-term vacancies (the municipality already has laws in-place which fine owners of vacant homes), typically sits between 1 and 2%. That should obviously go down to 0 as much as possible, but it's clear that (1) the problem has an extremely minor effect on the market, (2) it's not exclusively caused by investors, a lot of them are pied-a-terres or homes owned by temporary migrants working abroad and (3) the problem of vacant homes that can be attributed to investors, can be addressed in many other ways than a total ban.
In other words, not an effective or suitable policy on this point.
Regarding point 2:
The price increases aren't caused by investors in Amsterdam, studies have shown this over and over again. If buy-to-let is banned, rental supply drops, rental prices go in overdrive, and there'll be more pressure to buy under any circumstance. The have-nots who're unable to buy will be even worse off. There's no magical panacea to a lack of sufficient supply.
You mention a couple points around 2nd homes, which are fair. I think in a world where there isn't enough housing for everyone, we should at minimum disincentivize owning second homes that go unused most of the time. But apart from the fact that Amsterdam is the capital, a working town, not a place where people have second homes that they enjoy on the weekend, this policy doesn't address 2nd homes at all. You're not banned from buying and owning a 2nd home in Amsterdam after this policy goes into effect.
In other words, an entirely ineffective policy regarding point 2.
Regarding point 1:
There's no real issues with long-term vacancies (the municipality already has laws in-place which fine owners of vacant homes), typically sits between 1 and 2%. That should obviously go down to 0 as much as possible, but it's clear that (1) the problem has an extremely minor effect on the market, (2) it's not exclusively caused by investors, a lot of them are pied-a-terres or homes owned by temporary migrants working abroad and (3) the problem of vacant homes that can be attributed to investors, can be addressed in many other ways than a total ban.
In other words, not an effective or suitable policy on this point.
Regarding point 2:
The price increases aren't caused by investors in Amsterdam, studies have shown this over and over again. If buy-to-let is banned, rental supply drops, rental prices go in overdrive, and there'll be more pressure to buy under any circumstance. The have-nots who're unable to buy will be even worse off. There's no magical panacea to a lack of sufficient supply.
You mention a couple points around 2nd homes, which are fair. I think in a world where there isn't enough housing for everyone, we should at minimum disincentivize owning second homes that go unused most of the time. But apart from the fact that Amsterdam is the capital, a working town, not a place where people have second homes that they enjoy on the weekend, this policy doesn't address 2nd homes at all. You're not banned from buying and owning a 2nd home in Amsterdam after this policy goes into effect.
In other words, an entirely ineffective policy regarding point 2.