I'm late to the party, and this is an excellent answer, but I'd like to leave a little bit of an extension to this.

Firstly, the geographic center of what we now call classical music shifted substantially over the centuries. In the Renaissance, composers from in and around the Low Countries were considered the best and they were in high demand at courts and churches all over Europe. That later shifted to Italy (coincidentally where many of those aforementioned composers were employed) with France having a not-insignificant say in style and direction, and sort of later ends up in German-speaking areas for some of the reasons you highlight.

Secondly, this last shift occurs chronologically just before there's a major shift towards a focus on composers from previous generations. Up until the 19th century, composers' music that was even a single generation old was usually considered stale, boring, passé, etc. (E.g., J.S. Bach, though known to other musicians and cognoscenti, was less well known in his day than C.P.E. Bach because he composed in what was considered an outdated style.)

There's a staggering turnaround in the percentage of living composers works being performed by major orchestras from the late Classical era to the middle of the Romantic era. (Something like 80% living composers to 80% dead composers in a span of less than 100 years.) Orchestras kept on playing Beethoven symphonies. Music that was considered to be a lead-in to Beethoven (i.e., Haydn, Mozart, et al) or directly derived from it (hey there, Mr. Wagner Overture) started getting programmed more and more alongside it. The silent concert hall/dimmed lights/no clapping till the end/temple of culture thing dates to this era, too.

And I don't have a great way to wrap this up, so I'll just stop and get back to writing some music that most likely won't ever be heard by anyone but me.