MUJI explains itself:

Mujirushi Ryohin, MUJI in Japanese, translates as “no-brand quality goods.”

Theoretically, an item cost = (cost of production) + (cost of logistics) + (cost of brand). So a “no-brand” item should have higher quality per cost. However, no item I can buy has no brand; I know where I'm buying it, which affects how much I'd pay.

So I call these “anti-brands”, brands with spare presentation suggesting focus on production. The Ordinary has a similar spiel. While they don't seem like they're marketing to you, they're marketing to you through alternative messaging. I find myself averse to in-your-face brands, so that alternative messaging works on me.