Is there any evidence to suggest lowering CH rates increases competitiveness? From my experience with other gens(which is limited at the high level), it just makes crits much more significant and harder to recover from. A typical RBY game has many crits, so it's much more likely to even out.
Anyway, the core of the discussion is whether cart mechanics are THE factor that should determine simulator mechanics. It may seem obvious that they should be, but factors like convention, history and players opinions should be considered relevant, particularly for such an old game. I've been playing devils advocate a bit in this discussion, but hipmonlee summarised my views nicely. Sleep is a mess in RBY, so the best solution is just to ban it. Players don't want to do that, so the alternative is a simple sleep clause, or a more convaluted sleep clause that technically could would on carts but is essentially identical to what we have.
Freeze is also a mess, so options are ban freeze moves (players don't like), freeze clause or just live with it as is.
Comparisons to CHs etc. are silly really.
Anyway, whatever rule set you pick, there are arbitrary distinctions. Again, there's no legit way for me to get Mew or Surf Raichu using carts, but everyone's agreed on the convention.