What EFS posted above in ELI5 simply means there is no limit to how many post anyone can make in 24hrs however there is a limit in  posting intervals.

You have at least 6 minutes of wait time to make another post, so every 6 minutes as a newbie or brand new account you can make a post, and the idea is to prevent spamming from brand new accounts.

And for other ranks or with higher activities it takes at least seconds to make another post, I'm not sure how many exactly.

But however, it's also impossible that you will be able to make up a good post in seconds, so it regulates posting from bots