It's better to be a good programmer that's deeply experienced in a domain, then a great scala developer that doesn't understand the domains he's working in.
I'm more in the distributed space so I know elixir and scala very well with actor model and distributed coordination tools in my toolbelt. I'm not the best scala engineer but I can get shit done and it will be correct and work through all of the pathological conditions because I've seen a lot in this area. If you asked me to build a webpage I'd fall apart but I'm good at that specialization and have all of the tools I need to work with the technology I know today, and to build on to learn whatever technology is needed tomorrow (eg I've been working with elixir for a year but I'm extremely proficient at it because of my 6 years of akka experience)