Its an obvious conclusion. I would suggest that brainfarts and incompetence may also play a part, but I'm being kind maybe
Could be that would work in Wales of course, but my perception from cricket here in England in leagues where clubs are expected to put up an umpire every weekend for them to ump at other fixtures than their "own" clubs, is that this struggles as people don't want to umpire anywhere but their own club - they don't want to spend their Sat/Sun afternoons & early evenings spent with strangers. Then you maybe end up people grudgingly doing it, and possibly even the least able umpires as people get emotionally blackmailed into it to help their club, but they actually aren't very good umpires. The rule creates as many problems as it solves.
That's not to say it isn't worth pursuing as a concept of course, just that the end result may not be as meaningful as hoped
didds
I expect we'd see a similar problem in Wales - (most of?) these guys probably don't really want to referee and just see it as something they have to do as part of their coaching. I reckon their attitudes would be similar to the umpires'.
Some sort of monitoring might help - if clubs, or particular coaches, become known to be less than impartial an experienced referee or advisor (both of whom are likely already in high demand) could be sent along to have a look. Not sure if it would be practical or if it would really help if they are actually biased though.