Seriously. Clear your cookies or open a private window. All of the videos are replaced by the message "Try searching to get started". Granted, as someone who clears cookies regularly, I like the change.
I can imagine my mom opening YouTube (hypothetically) for the first time and seeing an anime video, or my younger cousin being shown a Top Gear video, and them deciding that YouTube is "that app with the weird videos" that's not for them. It's not a carefully thought out conclusion, but in the era of a hundred competitors, it's plausible that superficial decisions like that have a lot of impact on the app usage.
Or it could just be that someone with a forceful personality on the YouTube team decided this is how we're going to do it and nobody could oppose them, not every decision is scientifically planned and executed like it's often assumed from the outside!