> You're not generally limited by the supply of hotels
A strong strategy in Monopoly is leveraging the fact that houses and hotels _are_ in limited supply. There are only 32 houses available and you can't build a hotel unless you have 4 houses on each property in a set. If you end up with 3 monopolies with 4 houses on each property the game is pretty much over because nobody else is able to invest in anything.
Of course this would pressure the house hoarder into building hotels... Except each other player gets a set of dice, and on rolling anything higher than a 4, his hotel construction is thwarted by decree of the community's zoning board. UNLESS he's making deals under the table, increasing number he has to roll under to get approval from the zoning board.
And so on, and so forth.
That doesn't make Monopoly any more zero-sum. You're not generally limited by the supply of hotels. If I build a hotel where there were four houses before, the total capital stock has increased, not stayed constant.