They don’t even assume that anymore. If you look at the mean dimensions of sold phones in NL over the last 7 years, you’ll see that the ‘thinnest’ year is already behind us. Less then 6/7mm just becomes unwieldy for a lot of hands, and the sold phones dimensions reflect that.
I’ll still hop to Fairphone after my current phone dies. I would miss a great camera the most but a decent camera is still a decent camera. At least I’m the boss over my own phone, I’m so fed up with not being able to swap out parts myself like with a normal desktop.