You do you, bud. I'm not trying to convince you, I just thought the subject was interesting.

I don't recall exactly what his reasoning was, the talk was a few years ago, but it was something along the lines of true multitasking not actually existing. He said it was a myth, and what was really happening was that our brains were constantly switching our focus between these "micro"-tasks back and forth creating the illusion of multitasking. Multitasking as we know it is hurting our working memory, which in turn is what negatively affects our ability to focus among other things. If you search for it, there has actually been quite a lot of research on the topic, as well as the effects.

You know it's interesting, I had a professor in uni that did a talk about how people were destroying their ability to focus by multitasking all the time, e.g. listening to podcasts while doing menial tasks. He recommended specifically doing menial tasks, like washing dishes, uninterrupted and concentrating on just them, to improve our ability to focus.