Why would anyone want that future? There’s already more than enough technology getting between humans and having decent conversations.
(I know the examples aren't truly anonymous, but they're all broadly comparable to using a Twitter without your real name).
One example is proof-of-work. You can require a submission do 3-5 seconds worth of work on typical high end laptops/phones so that it becomes cost prohibitive for someone to post thousands of submissions an hour. There are ASIC resistant algorithms to prevent spam-for-hire services that might try to game the system.
Most users are passive consumers of content anyway so they wouldn't notice this process and when they want to post a few times per hour or day then the 5 seconds lag will be worth it to have a better social experience.