In fairness: The same goes and always went for house flippers.
There is no rule that states you may not sell houses to other people for gil. So long as you deliver the plot when the agreed sum is paid, there is no real fraud going on either, though some GMs named it such. There is no rule stating you may not hoard houses for resale either. House flippers were playing by the rules and went unpunished for a long time.
Do you know how they ended up punishing them? By interpreting the paragraph on "Disruption" very broadly, which states that you may not interfere with the gameplay experience of other players. This is such a broad term that you can apply it to any and every possible interaction between players, from early pulling over undercutting to house hoarding.
However, their gil wasn't taken away either - They got account warnings and bans instead.
