Every day there are posts here with some Twitter thread as the source.
This used to be just annoying in the past (because of the overall low quality of such sources), but now it's gone too far.
Twitter won't let you see the content without logging in anymore. At least this is what I see when I open a Twitter link and scroll down: https://i.imgur.com/E0h2CtQ.png
There are many free blog posting platforms out there that don't annoy users like that and — needless to say — are in a much more readable format. All it takes is a couple of minutes to sign up...
I think such a HN rule could help in promoting common decency on the web.
EDIT: A couple of posters made valid points against an outright ban. Someone suggested flagging paywalls/credential-walls. How about lowering the score for Twitter-link submissions (something like: 1 vote counts 0.5 votes)?
But if the tweet is highly important, has information people believe is valuable etc - then it gets upvoted towards the top of HN.
An outright ban on tweets also creates a secondary problem; what if there was some single tweet that was extremely important to the HN community. The inability to post it means people miss out on the news/discussion, until later on when it is re-submitted as a news story elsewhere.