The client did need to know.
There is a sharp distinction between attempting to access things and trying to create/overwrite/modify them. I have a need to expose that distinction.
As for the find/get distinction, I thought about that but decided against it because where get appears elsewhere in this codebase it generally means "fetch" and doesn't autovivify. If you and those around are consistent about it, find/get is a doable proposition, but I don't want to deal with someone in 3 months saying, "Why did it just create that?" and having to say, "Well, didn't you know to use find instead, unlike how it works everywhere else?"
I figure that people won't accidentally summon, and if they do try summoning, they won't be terribly shocked if summoning does something rather different than getting does. (Nor am I terribly shocked at the idea that a summoned thing could have been conjured up out of nothing.)