Pros:
If I want to lean how to change the carburetor on x model of string trimmer, there’s probably a dozen different videos explaining in detail how to do it. I can also order the replacement bowl float part for that particular model of trimmer and have it delivered in 2 days to my house.
If I want to learn linear algebra, not only can I do so, but I can watch all of the lectures from a course on linear algebra taught by a Harvard professor on the topic for free.
If I want to get the answer to a question from a bunch of strangers on the internet, I have a place to do that.
If I’m curious about a politician, I can read about their voting record, their donors, watch archival footage of their speeches and appearances, and have a much better understanding of them than if I had to rely on the occasional snippets on broadcast TV/Radio like people used to have to do.
You can find a community, no matter how niche, that’s passionate about something you enjoy. Interested in Japanese woodworking joinery? There’s lots of people and resources dedicated to it.
Who was the actor that played in that movie with that girl?—- Now you can find out, instantly. So satisfying instead of the thing nagging at the back of your brain for hours.
Cons:
There’s no arbiter of truth, so misinformation spreads quickly and dishonest people are able to weaponize disinformation.
Anonymity can bring out the worst in some people (That’s why the KKK wear hoods).
Communities can also be toxic. While there’s probably a group that focuses on native Algonquin basket weaving, there’s probably also groups that are white supremiscists, or religious zealots.
There’s a social detachment that seems to be going on with younger people who have grown up with the internet. It’s too easy for parents to sick a screen in the hands of their kids and not have to do the real work of parenting. It’s not healthy.