Ehh I don't buy that the market was ready 10 years earlier (in 2006) for open-source LSP implementations.

You gotta have someone write those language servers for free, and the language servers have to be performant. In 2006 that meant writing in a compiled language, which meant that anyone creating a language server for an interpreted language would need to be an expert in two languages. That was already a small pool of people.

And big multiplayer OSS platforms like GitHub didn't exist until 2008.