I was pointing more to the idea that some people thought it'd be a stupid mod to attempt to make and wouldn't ever be used by the majority.
Impossibility wasn't based upon what the engine will allow but rather what the people would invest into.
That topic is a terrible example of what you're trying to say. Pretty sure that people knew that it was possible to make a brick look like it occupied less space than it does, and the guy who made the suggestion suggested bricks that could exist on the brick grid as true 1/2 or 1/3 size bricks, instead of the mod you linked where there is a dummy space the brick occupies.
I don't know why you wouldn't just use the buildable vehicles topic, it's a much better example of what you're trying to say...