Different levels of structures' strength?

[Naamandre3]

Another way of doing it is to not allow tools to be used in an enemy town. You would have to break everything with your fists. Naturally, a thick cobblestone wall would be harder to break through than a wall of logs, and it's also possible to do with a server plugin.

Also the problem with this is cobblestone is just as easy if not easier to get in large quantities for wood. Why even bother building a wooden wall if a 3x better cobblestone is the same amount of effort?