journalists and reporters got banned and/or harassed -> many of them left the platform public news services got harassed and branded as state owned media -> many of them left the platform

Unfortunately not enough of those have left yet. News and journalism was the backbone of what made twitter big back in the day, and they still constitute a huge part of the traffic that keeps it alive today.

They seem to be among the last to recognise what associating yourself with Musks brand does for your own brand.