Maybe the problem of saying that JP voice acting is better in JPproduction comes from the fact that (assuming a non japanese speaker doesnt know japanese) non japanese speaker cant tell if the VA is performing well or if s/he is overacting or not putting effort.
I think that is definitely one part of it, but I think there are bigger aspects to it as well.
Usually the case is that English dubbing is poor because most dubbing of Japanese content is in anime where the companies that dub it usually get no-name actors or the direction/budget is low. Also, dubbing without full localization translation (making things relatable/understandable for the region being dubbed for) the quality drops in this way as well. Many themes and concepts may not be relatable in areas outside of Japan, which makes things feel weird.
When a dub is properly done with a nice budget with good direction with a good translation, the dub will be enjoyable.
Voice acting is much bigger in Japan than it is in English speaking regions, there is a lot more audio media, and the amount of well known/good voice actors is higher. This is likely the biggest reason people enjoy Japanese voice acting over dubs.
In video games, the dubbing budget is much larger, so things like FFX and FFXII have great english voices. There's also cases where you might prefer English over Japanese for a game like Kingdom Hearts, because of the iconic Disney character voices.
I would like to explain better and go into detail, but I think you understand my point.
