So, there are two ways of blocking resources in the game.
The first is to wall off / prevent an individual from acquiring resources with buildings that would prevent their acquisition. I think these represent a strategic advantage in PvP servers and I don't think that they're a huge deal. They're a little dickish in PvE but I think mods / admins can handle those as they see fit for their server. From what I've noticed, most admins are pretty fair with forcing a little access to things like iron or coal.
The bigger problem from what I've noticed is the ability to completely remove something from spawning by building near it.
This is especially huge for new players who don't know or realize they're blocking spawns, or also from those who are being jerks and attempting to remove spawns. It represents a development oversight specifically where a person can troll nearby resources by hiding or building well-hidden foundations that block resource nodes from even spawning.
This, ideally, should be removed. While I understand that it would be awkward or weird to have iron rocks spawn inside a home, it's less than idea that they don't spawn at all within some 30+ feet of a foundation.
On a PvP server this might not be a huge deal – equip some steel and go to town (unless it's a T3 troll. Have fun with that.)
On a PvE server, it's damning and creates a ridiculous amount of difficulty for the admins and the players as resources dwindle off and die.
This happens with just about every resource that I can tell: Thralls, iron, coal, trees, etc.
These items should spawn everywhere but ON TOP of a foundation. For thrall camps, you shouldn't even be able to build near them.