What this does is to tune the recommendations
for that session to what you view
for that session.
If you blindly follow some pratfalls or kittens video, you'll get served up junk. If you happen to be researching some specific topic (how-tos, explainers, academics, technical topics being among my favourites), you'll tend to find you're getting recommendations that follow from that initial topic.
I still treat recommendations quite warily, but at least the ones that come up in such sessions are somewhat better than standard fare.
(I never use YT whilst authenticated / logged in.)
