Unfortunately not. I believed it myself, until it became obvious it was a myth:
One interview went like this: They sat me down, opened up postgres, and said "Accomplish these goals." The goals were simple things like write SQL statements to query for certain types of users, or join data together.
I never had any reason to learn any of that. I knew that I could learn it if I needed to. I understood conceptually what joins are, why to use them, and what to avoid and why. The "why" is the crucial ingredient, and I naively thought that would protect me.
No... It's not fun when you have to sheepishly admit in front of three engineers that you have no idea how to write those SQL queries.
It was the same deal with Rails. Ditto for JS. Eventually I went through 5 interviews and struck out on all 5, in a row.