Considering how many outlets have covered this phenomenon and the dearth of videos of it you can find in the dark parts of the internet I'd say it's completely true. Downvoting doesn't make it false either.
Twitter doesn't have upvotes and I find it to be more addicting than sites with a upvote/downvote system. In a way, downvoting is still getting a response from a person, maybe that is why
I tried FreeCodeCamp (html & css) ~2 years ago. It was OK. I recommend you to finish the above one (Shay Howe) first, then try FreeCodeCamp. Actually, if you have got your own static web-page projects, you won't need the FreeCodeCamp for CSS & HTML. The kick-start would be enough and "Google is your friend" after that - learn more as you build your own projects.