[fantod]

> In order to undestand how these systems work I would recommend to know the language in which they are written. The biggest concern with Python is its poor performance hence the knowledge of a more efficient language will be a big plus to your skillset.

I think these two sentences are sort of orthogonal to one another. The first, I interpret as saying that it's useful to understand Scala if you're using Spark, essentially because of the law of leaky abstractions [1]. I think you're responding to the second sentence and in that case I agree.

[1] https://www.joelonsoftware.com/2002/11/11/the-law-of-leaky-a...