Old user here... I still don’t understand how Java failed at this. It was supposed to be the solution. You can, today, make cross platform, mostly native apps, with Java. But didn’t really become ubiquitous like we all thought.
* Non-native look and feel. Personally I think this is the big one.
* Applications/Applets took (take?) forever to boot. JIT takes a while to kick in.
* High memory usage due to heap+reference memory model and GC model.
* Latency spikes due to GC
* Installing a JRE is cumbersome for users
* Incompatible JRE versions are a pain for users
If I'm being perfectly honest, a lot of the problems people have with Electron were or are problems with JVM consumer applications.