Hygiene nowadays is a capitalists dream, it’s so easy to push irrational norms in this space. The commercials push for crazy things, washing your hair every day and then adding back the oils you just washed away with a conditioner, using some body spray instead of a baking soda based deodorant. Even toothpaste manufacturers try to scam us in using way too much toothpaste.
Not saying you should stink but honestly it is so much easier to be clean without using all those products. Plus it saves a bunch of money.
To be fair, my hair actually frizzes out when I don't wash it (with conditioner). It's fine for a day or two, but after that I should really get to it, because it also starts to itch.
You are right though, hygiene is a space of myth nowadays. Most info out there is bullshit.