Channel surfing, mainly. It's way easier to zoom around several different stations and keep up with several different games with cable/satellite because it's so much faster. YTTV added the very nice "skip" function to the Firestick platform this year, but that still only alternates between two channels, and it's still slower. Surfing 4 games at once as I used to do takes serious speed and preferably a remote that lets you alternative more than two channels.
The same thing applies to just checking out what's on another station. I can't just punch in a number on a firestick remote or even my phone. I have to scroll to a listing on the home page--if it's listed--or scroll down to a channel on the live menu, which takes a while compared to hitting "256" or whatever on a traditional remote.
There's another thing that doesn't affect me as much because we don't watch anything other than football, but if we ever decided to watch actual TV, YTTV (at least on the Firestick platform, which is how we access it in the living room) has a noticeable lag between the video and the audio. People's mouths are never synced with the words coming out of them, and it's intolerable. The worst part of football broadcasts is when the camera shows the announcers in the booth and their mouths don't match what they're saying.