Full-stack can be very different one (Score 1)

Do not forget that while client-side of full stack almost always is Javascript, the server-side can be dramatically different from Lua or Erlang to Java and Python - and there are very few of the people who can develop fast enough in every server-side language available. Client-side Javascript libraries also have a large competition / fragmentation, big corporations are pushing their solutions, while talented smaller projects (Elm, Vue,js) struggle a lot to compete just because there are no big names behind these. Imagine Python was developed by huge corporation and pushed and promoted, not because it's a nice language but because there is huge money behind it. Client-side also is going into wrong direction of cross-compiling (transpiling), creating unnecessary extra layer, instead of adapting much of ES6 and TypeScript in the browsers natively. It discourages browser developers to implement new features fast enough.