The leaderboard would reflect who's able to game the most likes, not who has the best house, so that's the largest and most obvious issue (which is already present in the current iteration of the leaderboard). If anyone was around for honor points, you know how that went. Anything that leaves competitive placement up to the community is basically opening up a pandora's box of exploitation. It'd be subject to all kinds of manipulation from guilds, large groups of friends, etc.

It's an issue that's similar to a rating-based spar leaderboard. The purpose would be to show who the best sparrers are, but it wouldn't function like that and it'd instead reflect who's able to spar the most carefully, seek out opponents they can beat, etc. I think the most important thing when suggesting anything competitive is looking at every angle of how it can be manipulated or exploited and molding your suggestion around minimizing or completely eliminating all instances of that.