In the comments, Rahul asked that question as follows:

In general perception, why are there no achievements in classical music that rival a Mozart, Bach, Beethoven etc. that were created in say the last 50 years?

Is it an exhaustion of what’s possible? Are all great motifs already discovered?

Or will we in another 50 or 100 years admire a 1900’s composer at the same level as a Mozart or Beethoven?

Or was it something unique in that era ( say 1800’s) which was conducive to the discovery of great compositions? Patronage? Lack of distraction?

I would offer a few hypotheses:

1. The advent of musical recording favored musical forms that allow for the direct communication of personality.  Mozart is mediated by sheet music, but the Rolling Stones are on record and the radio and now streaming.  You actually get “Mick Jagger,” and most listeners prefer this to a bunch of quarter notes.  So a lot of energy left the forms of music that are communicated through more abstract means, such as musical notation, and leapt into personality-specific musics.

1b. Eras have aesthetic centers of gravity.  So pushing a lot of talent in one direction does discourage some other directions from developing fully.  Dylan didn’t just pull people into folk, he pulled them away from trying to be the next Pat Boone.

2. Electrification favored a variety of musical styles that are not “classical” or even “contemporary classical,” with apologies to Glenn Branca.

3. The two World Wars ripped out the birthplaces of so much wonderful European culture.  It is not only classical music that suffered, but also European science, letters, entrepreneurship, and much more.

4. It is tough to top Bach, Mozart, Beethoven, etc., so eventually creators struck out in new directions.  And precisely because of the less abstract, more personality-laden nature of popular music, it is harder to have a very long career and attain the status of a true titan.  The Rolling Stones ran out of steam forty (?) years ago, but Bach could have kept on writing fugues, had he lived longer.  More recent musical times thus have many creators who are smaller in overall stature, even though the total of wonderful music has stayed very high.

5. Contemporary classical music (NB: not the best term, for one thing much of it is no longer contemporary) is much better than most people realize.  Much of it is designed for peers, and intended to be experienced live.  In the last decade I saw performances of Glass’s Satyagraha, Golijov’s St. Marc Passion, Boulez’s Le Marteau (at IRCAM), and Stockhausen’s Mantra, and it was all pretty amazing.  I doubt if those same pieces are very effective on streaming.  It may be unfortunate, but due to incentives emanating from peers, most non-peer listeners do not have the proper dimensionality of listening experience to proper appreciate those compositions.  To be clear, for the most part I don’t either, not living down here in northern Virginia, but at times I can overcome this (mostly through travel) and in any case I am aware of the phenomenon.  For these same reasons, it is wrong to think those works will have significantly higher reputations 50 or 100 years from now — some of them are already fairly old!

There are other reasons as well, what else would you suggest?