https://www.vice.com/en_us/article/j5wgp7/who-killed-the-ame...>The threat of software copies was recognized at least as early as 1976, the year Bill Gates wrote his infamous “open letter to hobbyists” bemoaning the illegal distribution of Microsoft software, but it wasn’t until the mid-80s that laws were passed banning the practice. The crackdown on software piracy was not evenly spread throughout Europe, however. Countries like the Netherlands, Greece, Finland, Sweden, and Norway didn’t have strict software piracy laws, if they had any at all, which allowed the warez scene to flourish there.
This is the hypothesis I've come to believe. Demoscene has always been tightly coupled with warez. In the United States, release groups had to go deep underground much sooner than their euro counterparts for operational security reasons.
If you were the feds back then, one of the ways to hunt a release group was to find its cracktro/demo authors who tended to operate a little more openly due to the larger demoscene. The release cells in scene groups would then cut ties with their own demo people for this very reason. Demo authors would then feel a lot less cool because they weren't as connected to the release elements of their own group anymore.
As of about 20 years ago, release elements of euro groups began operating under equally strict security regimens. I think in large part it came down to the fact their demoscene had more time to grow roots and flourish than the American scene.