I think it’s less “what you can conceal” and more “what won’t raise eyebrows in the company of people who may not be used to bigger knives”. Whipping out a big blade that comes to an aggresive point to cut wedding cake could get you arrested in some places, in other places, everyone would want to see your knife and then they’d show you their knife.
Myself, I carry a lockng folder but I also carry a Swiss Army Knife so if I’m ever in a place where it may not be wise to pull out my (new!!) Spydie, I’ll use it. Everyone loves Swiss Army Knives and aren’t concerned with them.