I know AdMech players have been complaining about chicken walkers due to a combination of pricing and availability since the army debuted so that could very well be a factor. I don't think they were ever this good before either?
I have a different theory.
AdMech has a very high skill floor and an equally high skill ceiling. The codex has a lot of moving parts and everything needs to be on/applied at the correct time on the correct unit. If you are able to play the codex well, you can crush. However that is quite difficult - it is very easy to get some sand into those gears and things can come to a screeching halt pretty quick. So GT
winning tournament players have the experience, computing ability and models and therefore can get the maximum out of the codex. The casual gamer however makes mistakes which drastically reduces the effectiveness of the army. If you transhuman/AP
-1/-2 the wrong unit or choose the wrong doctrina, you can get punished quick and hard.
I know even at 1k points its very easy to make this mistakes, even with few buffs and few worthy targets and then you struggle to win "even" against "mid range armies".