Protection should only extend to block breaking via non-TNT and block placement of things other than TNT/water/lava, so people actually make secure forts rather than just OH PROTECTION SO I'LL JUST LEAVE THIS CHEST OUT HERE
I think the main problem is that everyone just ends up with a stuff base or a base mad of obsidian. The roogedian fortress in the last viodestructo server was never directly attacked, but we know for a fact that the keep was TNT proof because it was made with obsidian, and the doors were TNT proofed. I think that a fort should be completely indestructible while a percentage of the population is away, because IRL people don't disappear off their property, the people there should have a chance to defend their land and the attackers should have to find a way to loot the castle by being sneaky or just killing everyone.