There are far more software project starts than good names out there. Finding a good name that is also not used by any other project can take a bunch of time and energy away from your code.
> Why would you want to fight with that software for page ranking?
The vast majority of software projects never make it far enough for the name to matter. You don't know which category your project will end up in when you start it.
> Why does this mostly happen to JS technologies?
Because JS is popular and makes it easy to start new ad-hoc code libraries. There are also a lot of half-baked libraries out there that will waste your time. So many developers end up making their own.