The argument made here is a good generalist tech guy would definitely think these things beforehand as much as an android or iOS guy ... That is language knowlegde !== problem solving ...
Any company that would hire me as a modern “mobile developer” would be absolutely foolish. I have only written 30 lines of Java my entire 20 year professional career, never written a line of Swift or Objective C. Why would they hire me over someone with relevant experience as a developer? If they want to hire me as a team lead/architect and then find mobile developers, I would know what to look for.