Even if wards were indestructible or some other anti-griefing mechanism was added; people would still find a way to mess things up for others. Duplicating your Portal names, landscaping as a griefing tool, killing bosses in a no boss world to enable raids, and that's just off the top of my head. I'm sure people dedicated to griefing would easily come up with a much longer and more inventive list.

Before you cry for IG to do something, be aware that if they switched entirely from creating content, fixing bugs, balancing, and addressing any other player issues, they would, at best, slow down or slightly inconvenience griefers.

Every multiplayer game has had some sort of this problem and I am unaware of *any* that have had long term success in eliminating it.

Server passwords that you only give out to people you trust is really the only effective and reasonable solution available.