Serial composition was an intellectual affectation which quickly fizzled out, and which has had no influence whatsoever on the music of the C20th.
Then why was it so difficult for non-serialist composers to get their music performed for much of the period?
I think that this a bit of an exaggeration, though there's no smoke without fire. As I've suggested previously, serialist procedures were and are just one of many paths to compositional salvation available to composers and I think that part of the problem in terms of its reception today is that a handful of its more vociferously dogmatic practitioners in the immediate post-WWII years sought to ascribe to it a kind of primacy that it neither deserved nor ever really even had outside their own circles.
I don't think it is much of an exaggeration, except that perhaps "serialist" should be replaced by "atonal". Look at what happened under William Glock in the UK, for instance. The neglect faced by composers like Scott, Rubbra, Lloyd, Arnell and many others. Still today I see newspaper critics sneeringly refer to any new tonal composition as "traditionalist" as if that were a bad thing.
It has not just died out - it's been actively jettisoned. Composers have instead taken greater interest in aspects of music which are not pitch-related - rhythm, duration, tempo, timbre, colour, overtone, instrumentation. In these areas, Schoenberg contributed nothing new whatsoever.
Schoenberg may not have directly done so, but his version of serialism led to "total serialism", which does extend serialist techniques beyond pitch.
Sure, but it's hard nevertheless to equate the suggestion that Schönberg eschewed - or failed to address - those non-pitch-related aspects of musical creativity with the actualité; also, I think it unlikely that Schoenberg would have felt attracted to seeking to explore total serialism had he survived for, say, a decade or more longer than he did. Do you think, perhaps, that his version of serialism did more to lead to total serialist practice any more than did, say, Webern's or Skalkottas's?
It makes more sense if we say "2nd Viennese School" rather than Schoenberg here. Without Schoenberg and Webern (I don't know how influential Skalkottas ever was) you would not have seen the development of total serialism later on. And certainly I don't think Schoenberg would have appreciated total serialism at all, had he lived longer. Obviously Schoenberg (and especially Webern) were concerned with more things than pitch, but I wasn't attempting, in the post quoted, to do any more than refute the idea that serialism per se is unconerned with anything other than pitch.
