I think that may be the crux of it. Once you are playing at the highest (not one of the highest) levels, it seems that whatever side can be put on the field according to the rules of the league should be a-ok. It should be the best of the best - and complaining about a team being "too competitive" for whichever reason, isn't appropriate. Whoever is doing the complaining is not understanding what it means to compete at that highest level.
But once you go down a rung or two (NL --> RL in this instance), artificially bumping up the RL strength to win a game that, by all rights, doesn't matter very much, is a crappy thing for a club to do. That's why there are rules in place to "artificially" keep the lower brackets fair, to ensure reasonable competition for all. Coaches used to be banned for a year if they were breaking rules and playing top kids down on lower teams. It seems that there is no longer much shame felt in it, or even an understanding why it's the case.