Earlier quoted context omitted.
I guess the main difference is JVM didn't have a workable UI vs the web?
You could do a working GUI with the JVM. But most people demanded Windows desktop apps, and for Windows only you could use .Net and C# for a better experience. Linux community was in big part against Java or Mono because of license and FUD so Python was the winner for the higher level language there.
Also, the Linux community wasn't against Java per se (not until Oracle bought Sun anyway) it's just that writing Java was a huge/complicated undertaking compared to say, Python and managing JREs was a huge pain in the ass. The old joke was, "By the time you have Eclipse open I will have completed the program in Python."
Lastly, mono was enormous (and still is)! Talk about bloated! When mono was being most actively pushed on the Linux community back in the day there was just no benefit: For smaller things you had shell scripts and Python. For larger programs you had C/C++, Java, and... Python :D. Why would you go through the hassle (and it was a huge hassle) of using mono when those other languages provided better performance with much lower friction/barrier to entry? It didn't have much of a "selling point" as it were.