Pause for thought, and some ugly self-recognition.
My antipathy towards Wales is probably not a coincidence, as you rightly surmised. Much of it stems from my playing days, as does my love for gallic flair from seeing Jean-Pierre Rives and Serge Blanco enthralling the crowd at Twickenham.
I played for a works team when Lincoln still had a few heavy engineering firms. We played at county third team level, and each year played against Market Rasen, sometimes their third team, sometimes their seconds, but invariably recognised their first team players temporarily demoted for the occasion, because the young farmers couldn't bear to lose to a team of oiks. I particularly remember Dobbs, their first team fly-half, and Chamberlin* (sic), a lock, both also three counties (Notts Lincs & Derby) regulars. MR also insisted on having their own referee in preference to a pool appointed one, a cadaverous-looking proudly Welsh daffodil**, who was crooked as a nine bob watch.
I jumped against Chamberlin, and he was always lifted, contrary to the laws in those far-off days, and despite him being 3" taller. This was pointed out to the ref, who pointedly ignored it. I was later on the floor on the wrong side of a ruck, and called the ref's attention to illegal handling. For my pains (and it was painful), one of their players stood on my neck and raked my right ear, after which I played on until half time before being taken to hospital in the same ambulance as our scrum-half, who had been knocked unconscious off the ball, and actually stopped breathing in the ambulance. Needless to say, they weren't penalised. I have the scars from a dozen stitches holding my ear back together. In another match, our outweighed but technically superior pack pushed over from a five metre scrum, and our scrum-half touched the ball down over the line, in the scrum, for a try. The Welsh daffodil disallowed it and tried to award a penalty against us, until our (Welsh) captain, who knew the laws inside out, let him know in no uncertain terms, that he would lead his team off the field, report to the relevant authorities, and ensure that the Welsh daffodil never refereed another game. White-faced, the ref awarded the try, to his team's astonishment and consternation. So yes, there's some history there.
I recognise skill and fair play, but note that Alun Wynn Jones is always prepared to bend both the laws and the referee's ear, also that, to my knowledge, Jonathan Davies has never awarded MoM to non-Welsh player. Hell, if he was given that responsibility in a Scotland Ireland game he would name a Welshman!
*When submitting a match report for the local paper, I always made sure he was called Chamberlain.
** Yes, I did type daffodil (of the narcissus family), on purpose.
Edit: Wow, that's some grudge I can carry! It would be an admission of failure to drop it now!
Edit2: I recognise and salute Josh Adams' magnanimous gesture. He's gone up massively in my estimation.