Facebook is huge influencer in the open-source world. I don't see anything wrong with learning the tools/languages that it adopts. There are far smarter people

Facebook is huge influencer in the open-source world. I don't see anything wrong with learning the tools/languages that it adopts. There are far smarter people working there. In context of this question, It seems that learning both Haskell and oCaml is what people recommend.