Pink Floyd and the Great Labeling Wars of '20

I am sure the 12 people that actually bought that album might agree with you. But even so, all the releases from Amon Düül II are varyingly listed across the internet as krautrock, space rock and progressive rock. Rather like Hawkwind, multiple designations. Your asinine need to put music into little bins is tedious. 

Sort of like one of the great psychedelic albums of all time, In the Court of the Crimson King. Which some sites list as prog. Which is silly, because prog wasn't even invented yet. 

You are funny, but only in an ironic sense. Yes, psychedelia was a dead letter by 1973. Amon Düül II had no "commercial popularity". "Commercial popularity" indicates selling more than 12 albums. Amon Düül II never charted in the States or the UK. Did not even make the top 200. They ended up disbanding. Get a clue.

Your view of psychedelia, European or American is misguided. Polka bands have a following, although they, like later psychedelic bands do not feature at all in the conversation of popular music. In fact, I'll bet polka  accordionist Frankie Yankovic sold more albums worldwide than Ash Ra Tempel and Amon Düül II combined (he did, I already checked, and by several million albums and singles).

Svetonio, your provincial Yugoslavian view of music has nothing to do with worldwide musical movements. The psychedelic movement as a music force was spent by 1973; in fact, for the most part it was done by 1970-71. Huge, important acts of the time like David Bowie, Alice Cooper, Deep Purple and Pink Floyd moved on from earlier psychedelic music. The post-psychedelic era had many of the more popular bands leaving psychedelia for prog, glam or hard rock, or in the case of Can and Tangerine Dream, abandoning earlier psychedelic efforts for Krautrock. 

Even the biggest bands like The Beatles and The Stones had moved on from their psychedelic period of the mid-60s (compare Sgt. Pepper's and The White Album to Let It Be and Abbey Road, or Between the Buttons and Their Satanic Majesties Request to Beggars Banquet and Let It Bleed -- nearly completely different styles). Additionally, your view that somehow prog music was the most popular in 1975-1975, and not the factual 1971-1975 time period shows you are clueless.

As far as The Grateful Dead, they began distancing themselves from strictly psychedelia even as early as 1973's Wake of the Flood, which is an amalgam of country folk, ragtime, R&B and jazz. By 1977's Terrapin Station, the album is listed on most sites as progressive rock/jazz rock, and not psychedelic. Because it isn't.

But please, keep grasping at straws, and posting videos of Yugoslavian acts that literally no is interested in but you, Svetonio. Particularly ones like Pop Mašina, who disbanded by 1978 because no one cared.