Uh, what? Why would you address this almost a decade after launching? Why would you call out people who post images to get around the limitation? Seems like grasping for straws to me...
On that note, the fact that images are being used to show text content on Twitter right now is laughingly unfair to folks who use a screen reader, given how much we value HTML for its presentation flexibility.
Twitter has changed CEOs four times since it was founded. It's never been a company with any kind of long-term vision or strategy.