Stockhausen has been largely marginalised due to this vice-like grip on his catalogue. As I understand it the vast majority of original recordings are only available from
www.karlheinzstockhausen.org, at pretty crazy prices, and without even a functioning web-shop (you have to order via email like it was 1992). This has made so much of his work way more underground than it should be. As an example you can’t buy a copy of Hymnen from
Amazon, it just shows a list of out of stock stuff right back to second-hand copies of the original DGG vinyl (which I have, obvs). This is insane as it is one of the core landmarks of electronic music. It is impossible to underestimate its significance and influence. Everyone should have access to this work. I’m sure it can be found on YouTube, though I’ve no idea if it exists on streaming services. Anyone fancy checking?