The single best way to turn off new players to the game is to give them a bunch of errata to memorize. Banning or restricting cards is much cleaner.
this game already has heaps of errata, bans, clarifications, restrictions, rules for different formats. add to this an absence of an up-to-date rulebook. all of this will always be a barrier for new players.
expanding the existing errata, bans, etc will certainly add to the problem.
the problem with lotr is this - it is a customisable card game with finite customisability because it is no longer in production. this makes established players start asking questions like - what would you change, etc. the questions are most likely hypothetical - but they don't have to be.
in the event that a PC ever gets up and running, part of their goals should be to simplify the entry point for new players. providing physical cards with actual errata (via printable pdfs) is a good stategy that has been used by other pc's to address the problem. i guess my point is, errata can be good for the game without turning new players away, provided it is done right.