600 is way too low. I've never been into Twitter but whenever I see someone's Twitter page they post like 30 times a day. Imagine how many posts the average Twitter user reads if they post that much.
This also breaks the algorithm-induced doomscroll feature of social media, and probably reduces advertiser value even further. Seems like a very obvious misplay even from the POV of an evil CEO.
The limit will probably be gone in a day or so. Elon just kneejerk reacts to things without consulting anyone, and this move is going to plummet user engagement. In the meantime, I hear Mastodon got a healthy user bump today.