Music people often sneer at folk music, I find. Music people sneer at popular music in general.
I know of not a single musician for whom I have respect that would do such a thing. All of the great composers, particularly of the late 19th century acknowledged the importance of folk music and often used them. Look at Tchakovsky, Vaughan Williams, Janacek etc. Again, the idea of sneering at folk and 'pop' music is a very recent one, and one that is also quickly becoming unpopular again, for the betterment of all music, IMO.
Putting "Gregorian Chant" on that list is another thing which I have a big objection too. Plainchant is a style that spanned 5-7 centuries, and which itself evolved so many times, from simple melodies all the way up to the rich polyphonic textures of the early baroque. I recently bought a boxed set called "Sacred Music" giving a tiny snippet of the sacred music of Europe from the 9th century all the way up present day (including Leonard Bernstein, who wasn't European, as you probably know.) It consists of 30 CDs, the first 4 of which consist entirely of chant, and the following 2 of which consist of early music based on chant. Putting "Gregorian Chant" up as a thing is like putting, say "Rhyming Poetry" on a list of literature that changed the world.
The classical music tradition is a visual one - there are plenty of composers and musicians who lost their hearing but were able to continue composing and making music - Beethoven, Faure, Evelyn Glennie, etc., but no BLIND ones.
This obviously doesn't include the French tradition: Vierne, Widor and Langlais were all blind, Vierne practically from birth, and he wrote some of the best French organ music we know of. Widor and Langlais were also visually impaired from a very young age. They each wrote a mass for double organ, and a number of Symphonies which were so popular they had to be transcribed for organ so that they could be regularly played at services.
My own counterpoint lecturer is 80% blind, and he has composed some exquisite pieces for choir and organ.
This big line that is drawn between so-called "classical" music and pretty much everything else is an absurd one to draw. In the words of Bernstein himself: "It's all music"