> It seems our fingers have gotten thinner

Of course not. It's actually way simpler: smartphones became taller and heavier and you no longer can use it with one hand anymore even if you are 2m tall man. So the main mode of interaction changed to a two-hand mode and one-hand is relegated for the doom scrolling, selfies and quick replies.

Hell, my Moto has a special one-handed mode!

>> Use one-handed mode

>> Want to use one thumb to navigate your phone? Turn on One-handed mode.

>> This mode is only available if you're using Gesture navigation.

https://en-us.support.motorola.com/app/answers/detail/a_id/1...

Trivia game: try to guess to which smartphone these dimensions belongs to:

    115.2 mm   58.6 mm   9.3  mm  137 g
    130.7 mm   68.9 mm   8.99 mm  145 g
    146.7 mm   71.5 mm   7.4  mm  162 g
    163.0    × 77.6    × 8.25 mm  227 g

Just curious: why your otherwise neatly formatted table uses a different format for the last row?

As an aside - I am a slightly under 2m tall man and I still use my phone with one hand. I still use a 7” tablet with one hand as well.