These threads come up from time to time, and while I always find them fascinating, I’m afraid I’m too long-winded to give brief replies.
Last 50 years, huh? Well, how about Alexina Louie, R. Murray Shafer, Arvo Pärt, John Adams, George Crumb, Jake Heggie, Julien Bilodeau. There are lots more, but I don’t think of any of them as household names…
One of the interesting things about today is how our aesthetic has expanded to include a greater range of musics than at any other time in history. Consider - in Beethoven’s Vienna (to focus on just one of many interesting cultural places and times), Folk music was not very highly regarded (except as a source of melodies for serious composers to arrange), music of non-European cultures was disparaged if any attention was paid to it at all, and most importantly, very little attention was paid to the music of 100+ years earlier. Mozart and later Mendelssohn revived the music of Bach, who had been writing 30 - 50 years previously (give or take, depending on the piece.) In Bach’s day, New Music was the norm - I often think that Bach would be astonished that his music is still being played 250 years later.
Whereas now, we have a greater access to different historical periods, cultures and styles of music than ever before. Beethoven was in competition with his contemporaries; a 21st century composer is competing for attention with every composer who has ever left us music, not to mention every genre of music that humans have conceived.
The 20th century was a time of great exploration in ideas of how to organize music, and one of the side effects of that exploration was a polarization between practitioners of different styles. Boulez, a strict serialist, broke off with John Cage when Cage began to explore aleatoric music. Schoenberg and Stravinsky hated each other; Bartok made fun of Shostakovitch in his ‘Concerto for Orchestra’, and the list goes on…
Fortunately, as Edgard Varèse said (and Frank Zappa quoted him often), “The present day composer refuses to die.” And on that note, (Ha!) I need to sleep.