It's easy to forget, but for years after its introduction JavaScript didn't work well. It was extremely slow, limiting the complexity of what could be built with it. There were problems galore with cross-browser compatibility of what was written. There was no reliable vector graphics or canvas system, so you really couldn't do much graphically. The DOM interface was hard to understand to be charitable. It didn't run outside of the browser, so how dare you call yourself a developer if you were using it?
To the extent that developers knew JavaScript existed at all, it was not considered a programming language.
These things started to change in the early 2000. So deeply ingrained with the disgust for JavaScript, that it took a very long time for the consensus to emerge that you could actually build very complex software on a post-V8 runtime.