I think the problem comes from living in a bubble. We all live in a bubble and think of the reality around us being the reality for everyone else. It's not until you step outside of the bubble do you realise the assumptions ions aren't necessarily true. What will often be the case is different people solving different problems with different languages. Sometimes it's down to the suitability of the language, sometimes it's down to the local skill set and sometimes down to what's considered to be the latest trending language.
Learning a new language takes a time investment and changing the way we approach coding problems.
As a Java developer I am still wrestling with whether Scala will end up supplanting Java or whether it will be a side language that will simply influence the direction Java takes in the future?
For me languages fall into three main categories, those that stay in the main steam, those that influence the main steam languages and those that simply fade away, because they have been replaced by something 'better'. For the influencers they sometimes stay in the background because while innovative don't necessarily add a reason for such a radical change and by the time the look like they may be gaining steam, they lose it to the fact the 'mainstream' languages have picked up the best features.