Hello,
I would like to add my two cents about this.
Shaq Jenkins wrote:A below average player will completely ruin 3+player games such as Puerto Rico, Tokaido, Legendary Inventors, etc. since they will inevitably make questionable moves that imbalance the game.
Being a beginner, I clearly have been —and certainly will be— responsible of such "bad moves", leading to a less pleasurable game experience or even to frustration for better players.
* I felt some empathy about it.
I perfectly understand the wish to have a more accurate restriction system and that such feature is desirable (even for me, when I'll hopefully be better

).
* But it made me think.
May I suggest you and others to consider it from another, philosophical (?), perspective:
Let's say player A is a beginner, whereas B and C are equally good.
- The rules were chosen to get a game as balanced as possible (at the beginning!).
- B and C take as rational and optimal decisions as they can (as do A, by the way
) —building on their experience, making assumptions about other players' actions;
- A makes an unexpected action, non-optimal (or even stupid) for his/her score; It is regarded as irrational from B and C;
- The action affects B negatively and C positively. The action "imbalances" the game (from their viewpoint, at least).
- But the rules allow this action, right?
So, should player B (and C) blame the game?, player A?, the interface allowing players to join around the game?, or maybe life (another game with its own rules)?
My opinion: none of them (or all of them, + B and C themselves, and of course: bad luck). Why?
Because B and C did not take into account the possibility that A acts in an irrational way: surprise!

They were confident that A would act as in their experience, without considering the
uncertainty hiding in the game-experience otherwise set as a Swiss cuckoo clock.
I'm not saying B is not good. B may sometimes reverse the situation if s/he masters the game. Otherwise, well, it's just bad luck. Yes, even in games designed for less randomness, the reality of life, evil uncertainty, comes back! (and life sucks, sometimes

) —and
that is, in my opinion, exactly what frustrates (us) players, who wish to control everything.
Again, I'm not saying it's always a pleasure to play with players of different levels. That's just part of life. Even great masters may fall when they meet with "bad fortune".
All the best,
Thierry