Conventional wisdom is quite the opposite.
Only b/c UA had more way more FF'ers thus have a bigger presence on the merged FT forum.
The old CO forum was great, now it's a bunch of whiners who won't acknowledge anything that CO did to improve MileagePlus, and it's quite a lot.
When I flew UA in the past it was with surly FAs and really beat up planes. Never had a very good experience. As a combined airline they brought together a lot of bad elements but many good ones as well.