@aperson,
It is a simplistic and disingenuous position for your friend to have taken. "Today," we have composers (John Williams is an example) who write musical scores for orchestras which are very bit as complex as anything written by Vivaldi, Hadyn, Schubert or Sibelius. Within the recent modern era, composers of "classical" music (using the term classical in its less precise meaning) have written scores for motion pictures, which is where "classical" music "went" when it no longer commanded the attention it once did with the public. So, for example, Sergei Rachmaninoff both wrote scores for motion pictures, and appeared in them as a performer. Although he did not write the original score, Dmitri Shostakovich wrote a new musical treatment for Sergei Eisenstein's famous 1925 silent motion picture,
The Battleship Potemkin, and it is Shostakovich's score which is most often heard in modern restorations of the movie.
Aram Katchaturian, an Armenian composer, wrote the truly beautiful score for the motion picture
Spartacus, which he then rescored as "symphonic pictures" for public performances by symphony orchestras. Eisenstein's 1938 motion picture
Alexander Nevsky was scored by Sergei Prokofiev, who then reworked the score as a concert contata for orchestra.
So, comparing The Beatles or Coldplay to Mozart or Beethoven is a glaring case of comparing apples to oranges. There was popular music, and popular minstrels in the days of those composers, and there always have been popular music and popular minstrels. In addition to composers from the Baroque, Classical, Romantic, Modern or Neoclassical, there were the composers and lyricists of popular music which was never intended for orchestral performance. And composers of orchestral music have deeply mined popular and "folk" music for their own compositions. One of my favorite pieces of orchestral music is Joseph Canteloube's
Songs from the Auvergne, scored for soprano and orchestra. It is based on the folk songs of the Auvergne, a region of France. Another of my favorites is the
Bachianas Brasilieras by Heitor Villa-Lobos (a Brazilian composer, the son of a Spanish immigrant, which explains the name). It is in nine suites, all of which are, allegedly, written in the style of J. S. Bach, but based upon popular Brazilian airs. One is about a small steam engine which labors up a mountain in Brazil, and uses the orchestra to imitate the sound of the little engine, in a supposedly Baroque style. My favorite is No. 5, scored for soprano and eight cellos, and based on a haunting melody which is one of the most popular songs in the Brazilian song book.
So, your friend is either profoundly ignorant (which i doubt) or is playing a silly game of comparing apples to oranges--ignoring that while Wagner was writing his operas, Stephen Foster was writing popular songs based on melodies of the American South, and traditional folk songs, most of them from the slave and former slave communities. He is ignoring that while Lennon and McCartney were writing their songs, John Williams was writing a score for the movie
The Valley of the Dolls (the movie is appallingly bad, the music is wonderful). Williams is probably most famous for writing the score to
Star Wars. George Gershwin successfully combined popular American music, particularly jazz, with orchestral scores to make a very successful career with both musicals and orchestral pieces. Gershwin asked Maurice Ravel if he would give him some lessons in composition. Ravel asked Gershwin how much money he had made the year before, and when told, said to Gershwin: "How about you give
me some lessons?"
The next time you see your friend, tell him: "Oh, piss off . . . you're comparing apples to oranges."