> eventually it creates such a powerful incentive for competing rental supply to enter the market But that only works if additional supply is allowed to enter

> eventually it creates such a powerful incentive for competing rental supply to enter the market But that only works if additional supply is allowed to enter the market--which in a situation where rent subsidies were even necessary in the first place, is overwhelmingly likely to not be the case. In other words, the actual problem is that rents are too high. The correct "fix" if that is the case is to allow new supply to enter the market; but if you are doing that, rents won't be too high in the first place, because supply and demand are allowed to work. So if you actually have the problem of too high rents, it's because you aren't allowing supply and demand to work--and in that situation, subsidizing renters just makes the problem worse, by reducing the incentives of existing landlords to do anything to improve things.