It's because when users reply to old threads, it notifies everyone that was in them, which for most can be annoying to receive notifications from old content.

@ImaginationStudios8 Official wiki account Fair point.

Why can't we respond to comments only a month old? The wiki is super dead

I remember I was trying to tell KP Ravenclaw their au was amazing

Then that Mario mod guy locked the post saying “don’t reply to old threads”

@Xtremeyoylecake5 don't respond to old threads.

@BrainsofaWeirdArtist

This thread isn’t even that old