Yes, that's right... making stuff up. Never actually saw a Dev make a comment on this. Never read the reason for the limitations anywhere. Never saw them comment on why Castles and Keeps and larger than 18x18 plots weren't available.how do you know that? as far as I know, when you crate a house everything goes in a crate under the plot that takes up 1 square. seems to me you are just making stuff up.
I'm sure they just arbitrarily chose some number...
Probably didn't test it at all.
And me, I just make it up as I go along.
</sarcasm>