> Also I imagine if everyone started blocking real retweets like this people would just go back to the oldskool copy-paste method.
Yet, other networks where retweeting (reposting) requires copy-paste has a much lower percentage of this. Anecdotally, almost nobody in my instagram feed are reposting other people's photos or text. There are applications to do so, or one could just copy-paste a screenshot. Yet, most people post only their own photos. On twitter, almost half of the posts I see on the first page are reposted retweets. How does it look for you?
Also, Raising the bar very little would make a huge impact due to the amplification of the network effect.