I am an active Twitter user and I know what you mean by screenshots of walls of text. There is no endemic use of such modality across Twitter, with few exceptions.

I stand by the statement that Twitter moving into publishing long-form content puts it on the same pedestal with Medium and defeats the purpose of the platform. Which is OK - strategy evolves, and someone did the math that this is going to be more beneficial.

My other comments reflect my stance on their decision, but I am neither a product manager at Twitter, nor do I have any knowledge of the "whys" so take this with a boulder of salt.