Seems that resists have been going up in the game since 3.1s release. Check out the thread at
http://forums.lotro.com/showthread.php?t=320848.
It does have a short acknowledgement by Turbine in at least two different entries.
Seems that if the mob is higher than you, the more resists/resistance to your tactical skills. From some of the replies, I guess it effects end game instance/raids more than anything else.
