It's impossible to be an expert in everything, but it's very doable to be competent in many areas. I just don't see the problem in being quite decent,for exampl

It's impossible to be an expert in everything, but it's very doable to be competent in many areas. I just don't see the problem in being quite decent,for example, at Vue.js and Kafka and Postgres. Let's say you have been working with Postgres during the last year: you are very competent at it. Now, for reasons, you need to work on the client side app of your company: you don't know Vue.js, but you go and read the documentation (as any competent dev would do). You spent months learning and working on a SPA, and you spent less time with Postgres. Done. Now you're competent at Vue.js (it doesn't take years to get competent with Vue.js, but certainly it takes years to become an expert). You go back to work on your daily tasks with postgres. And now... You have to deal with Kafka. Rinse and repeat. Perhaps then later in 2 years you have to work again in the front end, but this time with React: easy, you already know Vue.js., so knowledge is transferred.