Because people could just claim it was a spelling mistake fix + Every user not in the top 10 would always put "edit: thanks for the 100 upvotes! I'm new here so it really means a lot!"
MopMan Announcement Template:; Is it just me who thinks that the ability to edit comments would be a bad idea? It would be hard to implement, perfect for trolls and an overall pain for the average user (if you want to correct spelling mistakes just delete your comment and post it again with correct spelling?)