I think it is somewhat similar to the issue of port begging. In isolation, one person saying that they would be interested in having a game come out on System X is not problematic, or at least relatively innocuous. In practice, before the mods made the decision to become more strict about port begging, conversations about games would end up being not about the games but instead devolve into consolewars arguments about the relative merits of the consoles and which one would make the best home for it and how realistic a proposition this was and so forth and not about the game itself.
Similarly, many posts in the "would" category might not be all that bad taken in isolation, but collectively become problematic. I am not saying that these things are strictly equivalent to one another - and I personally think that "would" has its own inherent problems that port begging does not necessarily have - but simply that the approach that moderation takes these issues has that parallel.
