I fail to see where what you're saying would provide ANY benefit for replacing media queries or the code inside them. It just looks like you're telling mobile users to go **** themselves by feeding them absurdly undersized fonts, and/or punching 4k users in the face with absurdly oversized fonts.

But then I suspect you've got a lot of flawed methodology in your code, given that if you have to say "screen and" in your media query, there's something wrong with your <link> tag.

I also suspect you don't even know what EM/REM even is, since you mention the 16px default but not that users can change what that default is. Such as on my laptop where 1REM == 20px, my 1440p IPS workstation where 1REM == 24px, or my media center where 1REM == 32px by "default". The very audience for designing in EM/REM in the first place!

A suspicion supported by your putting up that 62.5% amount, an old LIE people used to use to set 1EM to 10px, when in point of fact 1EM / 1REM could be ANYTHING.