Things that could more easily be argued to be important would be stuff like academic content or news content.
At this point Youtube is a part of the broader internet infrastructure (as are many other large social networks), and you can make an argument that it's a bit like any other utility (roads, phone lines, fiber op cable, GPS satellites, etc).
government offers schooling. if you wish to seek additional, that is offered in other ways. when i went to school, YT didn't exist. yet, i still sought out additional resources that were available outside of school. this argument carries no weight with me.
news content is available in other places. these news sources choose to offer their content on YT because that's where the audience is. if YT were to no longer exist, the news content would still be available elsewhere. again, no weight here either.
considering YT part of the infrastructure means to me that you are very confused on what infrastructure is. YT utilizes that infrastructure. if YT didn't exist, it does not mean that the internet wouldn't work. it would not prevent anyone from accessing other resources utilizing the actual infrastructure of the internet. so either, this word has a confused meaning for you, or you're just beyond hypothetical and not realizing it. i realize some people would feel like the internet was broken if social media sites were down, but they'd eventually get over it if they were to never come back
There is plenty of academic literature which explores the concept of social media as infrastructure. I didn't come up with the idea, I only pointed to it.
I won't point to any specific document, but there is plenty of related material here: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=soci...
Or, take a look at the wiki page for "infrastructure" to get a rough sense of how broad the concept really is.
What more do you want? I essentially sent you to the entire corpus of human knowledge lol.
Great!
Go back to school and let us know what you find? Yes, school is important, and schools from time to time lean on YouTube content (from authoritative sources, generally, because not all videos are from internet randos).