Have you ever tried typing on a keyboard without them? They're one of those things that you don't notice consciously but is actually really important.

Not sure I'm using them even unconsciously. Because every time (admittedly not often) that I get a new keyboard I type shifted (as in djogyrd instead of shifted) for a while.

If i'd be using those raised markers I wouldn't take so much time to adapt I think?

I’m 33 and was the mostly the same until I switched from QWERTY to Colemak. Now my index fingers practically live on the f and j keys.