The power/heavy metal scene/fanbase in Germany took off in the late 80s/early 90s extreme metal rose elsewhere, it solidified as the same styles fell out of popular favor and nearly disappeared in America. Manowar solidified their reputation here - charting top 10 in 1992+96 and selling 250k+ copies of a few albums in the early 90s. There was a responsive fanbase there that supported bands and offered the theater for the audience they needed to sustain their spirit. Germany has been a great place for metal for many years now, still supporting 80s USPM bands to a much greater extent that the US does.
Despite the strength of the scene in Germany, the US had an expansive and unrivaled variety of amazing heavy/power/speed metal bands in the 80s. In the limelight, they existed in the shadow of mediocre cover/butt rock bands of the time, but there was quite a diversity of amazing bands from places far from the major scenes in LA, SF, and NYC. Of interest to the DMU philosphy, there were a lot of bands who really captured the spirit and ideologies of heavy metal in their own ways, and often saw little success, sometimes even no distribution until the file-sharing age. Of course, this is mostly outside of the nihilist/dm/bm scope that has been focused on, it hasn't really been on this site's agenda, I suppose.
There were bands who came out of all parts of the huge country: Manilla Road came out of Kansas and I'm sure you all know them. Shok Paris and Black Death from Cleveland, Ohio, Enchanter from Jackson, Michigan, Fates Warning and Liege Lord from Connecticut, Queensryche and Heir Apparent from Washington, Crimson Glory and Savatage from Florida, Powerlord from Oklahoma... the list goes on. There was great diversity in geographically separated bands, they weren't homogenized like bands in LA were to an extent, and even then, a scene like LA could support a nerdy sword-and-sorcery fantasy band like Cirith Ungol who did things there own way and were absolutely killer and top-notch, despite being radio-unfriendly. At the same time, there were also thrash and doom coming up in the US, and there was overlap in the scenes. Death metal evolved at the same time too - Possessed's "Seven Churches" Fates Warning's "The Spectre Within" came out within a day of each other.