John Schick asked:

"I wonder if Mozart or Beethoven had any of these problems?"

Actually, they knew each other and did "borrow" from each other. Mozart was older, but they were in contact. In most of those eras of music, composers "heavily borrowed" from each other. It was actually expected and accepted. Musical scholars today will make all kinds of comparisons and accusations, but at the time, it was considered the sincerest form of flattery.:

https://en.wikipedia.org/wiki/Beethoven_and_Mozart

MAB