How do you Know This ?

One thing about the internet in the link. Double click on a link, and you are there.
If you want to show someone where you got your information, it is very, very easy to insert a link. This also allows your reader to find out more about the subject, or maybe check out the context of some comments that you quoted.
This is one way where online discourse is different from other media. On TV, you only see what the editor wants you to see, and have to take their word. In print media, the same is true, except in academic journals where footnotes are used.
If you submit a paper in school, you best show where you got your information. Plagiarism is serious business.
You would think that using links to show your information would be universal. It is so easy, and gives what you say credibility. An exception to this might be when someone says something questionable. If you ask for a link, you can expect to be insulted. This would indicate that the statement in question is not accurate.
The internet is in a wild west phase. You can say almost anything you like, and hope that people believe you. It is in your best interest to help them by showing where you got your information.