You're wrong about that. There are lots of unrealistic things like my halfling running up the fighter and being tossed up onto a dragon that is in mid flight. It's not realistically or narratively possible, but absolutely possible in a roll for everything game. There are a bunch of ridiculous scenarios where the DM deciding based on realism or narrative sense will say no, but roll for everything makes it possible.
Now there is some overlap where a DM deciding everything will say yes on things that the Rolling With It allows a roll, but those are also not the same, because the on the one hand success is guaranteed because the DM said yes, and on the other hand you can fail a roll.
There is always a difference between the two styles. How much of a difference is the only thing to figure out.
Then we agree about that anyway.