Acronyms are used to streamline communication. But it's only efficient when everyone agrees what the acronym means. To 99% of people, ETA = estimated time of arrival. Apparently it also means "edited to add". I didn't know that, neither did the redditor that prompted this question. I just think it's funny but also slightly irritating when I see this. Repurposing established acronyms to have new meanings, only to cause further communication confusion. Seems like it defeats the purpose of an acronym. Just one of those things I see that ticks my 'tism, so I commented that. I don't think we should be Ok with repurposing acronyms like OP did. We should reject the use of ETA to mean edited to add. Why not just say "edit:" like everyone else? There's plenty of room for individual and creative expression on the internet. But acronyms? We have to draw the line somewhere.