> LLMs won't add information to context, so if the output is larger than the input then it's slop

That doesn't align with my observations. A lot of times they are able to add information to context. Sure it's information I could have added myself, but they save me the time. They also do a great job of taking relatively terse context and expanding upon it so that it is more accessible to someone who lacks context. Brevity is often preferable, but that doesn't mean larger input is necessarily slop.