It does say "default" which implies you can turn off the filter, but yeah it's not very clear and does make a big difference. For example, YouTube already won't let you view flagged content without signing in.
This is how Youtube works now. Age restricted videos can't be viewed without logging in.
Yeah. Can’t watch king of the streets or some video game trailers.
Ah yes. How terrible would it be if an angsty teen watched the music video to Linkin Park's Numb. Truly the end of the world.