While I think it’d be neat, I doubt Damage Blocked would be as simple to implement as most scoreboard tweaks. I don’t think that damage that gets prevented (by blocking, dodging or staggering enemy out of attack) ever actually gets calculated, so it cannot be directly tracked. Stamina Lost or Hits Blocked would be easier to track, and wouldn’t be that different. Of course, Stamina can be lost from Troll bile, Halescourge’s attacks and Convocation’s pool, and Hits Blocked doesn’t separate between different types of hits. The former can (and should) be avoided though, and the latter problem exists on the Damage Blocked version too, so I don’t see either as significant.
While we’re at it, changes to the Scoreboard have been requested since the VT2 Beta, some bigger and others smaller. The primary reason being that the way it is right now promotes aggressive play (even if dominating the scoreboard gives no tangible rewards), emphasizing killing and dealing damage yourself above actually playing as a team. While you can use some aspects to follow your skill progression, it already requires quite intimate knowledge of the career you’re playing and its (and your) playstyle. And obviously, following the progress on more team- or defense-oriented Careers (RV, IB, WHC…) is a lot harder, with reviving and Damage Taken being the only good stats to track.
And yes, Friendly Fire tracking would be useful in the base game too, but unfortunately as the mod is on the Approved list, we are unlikely to get these tweaks anytime soon.