Final answer:
Juliek and the musicians weren't allowed to play Beethoven due to anti-German sentiment and acts of patriotic conformity during World War I, when German composers' works were widely shunned.
Step-by-step explanation:
Juliek and the musicians were not allowed to play Beethoven due to the political and cultural climate during World War I, where anti-German sentiment was strong in the United States. During this time, acts of patriotic conformity took place, and being from German or Austrian origin often led to discrimination. This resulted in orchestras ceasing to play music by composers such as Mozart, Bach, Beethoven, and Brahms. This was part of a wider push for patriotism where anything associated with German culture was looked upon with suspicion, sometimes even resulting in violent acts.