That logic is dubious at best. The more likely scenario is that European defenseman who struggle to graduate from the AHL do so because they don't adapt well with less time and space. Often times this is guys with mediocre skating, like Honka and Juolevi.
There are plenty of NHL defenseman who came over from Europe and spent lots of time in the AHL.
Take this in a good way. This doesn't have to mean you are wrong in anything else, but...
Juolevi wasn't that bad of a skater before his injuries? Ask London Knight fans if you don't trust me regarding OJ.
Honka? You are so wrong here and just spitting lies. One of his strengths and actually his brothers too was their skating. It wasn't great perhaps but no weakness whatsoever and probably good or good enough. Just ask Dallas fans themselves. Honka seemed to decline when he didn't get the opportunity. When it came to the Honka brothers it was always the IQ and- or the competing level.
I mean you can twist and turn things as well. Heinola was better than all Canadians and North American D's at the WJC's, I mean big time. Offensively he's been ready for a while but sometimes the wrong franchise draft them and they need to stay behind or wait too long for their opportunity. That is and will always be a factor for young players to take the next step.
I mean Ristolainen was never close to neither Heinola or Niemelä at the same age. These other two had IQ and finesse on a whole other level. But... None of them have made it yet. When it comes to Heinola I blame the Jets big time. Niemelä has to fight against other decent and young D's but he will probably and eventually make it.
If you want to make a valid argument then do your research and don't claim things just because you want to be right in another debate. Can't understand why people liked that comment, guess they never saw these players (Honka & Juolevi) actually play when they were 17-20 years old.
Cheers.
Edit: Also, Nemec has talent and will most likely make it. Though I was always a lot more high on Jiricek, especially offensively and when it came to early success. But I guess that's somewhat irrelevant.
But again, don't underestimate the fact that some talents need more confidence and time even if they have more potential in the end. Dahlin comes to mind, he pretty much sucked at times and I still think he can very inconsistent in his efforts. Sloppy with the puck etc. But that doesn't exclude the fact that he can be a difference maker in the end and has some brilliance in him. Also, it doesn't mean the AHL would've been better for him.
My point, try to dump that black or white perspective. It's too simple. Every individual is unique, just like every franchise can be. You guys can compare all you want but don't try to fool yourselves that you know everything and so on.