Communities used to be on specialised forums and blogs. I've watched my favourite specialised blogs turn off comments because of bot spam, and I've watched forums raise the sign up bar and browsing restrictions for similar reasons. Reddit's anti-spam measures plus moderation makes it a much more decent experience.
> Communities used to be on specialised forums and blogs.
Now these communities are on Discord, which is not the friendliest to look for archived knowledge. If Discord can solve the UX for knowledge share, I can see it as the product with the better chance of replacing Reddit.
