No, not complete bollocks.

Learning new languages does add different layers to your personality.

I am native-level fluent in three languages, and have some level of fluency in three more.

Learning a new language opens a complete new door to a new culture, and way of thoughts through books, movies, songs, and so much more.

Even if you don't spend time to learn a culture well, i.e. don't listen to music or read literature, learning a new grammar, and very importantly, new words, do reshape you, and gives you new perspectives and ways of thoughts.