There are several reasons I might prefer a fixed blade over a slippie for a given task but no way it needs to be a 5" or larger knife, especially for EDC. (If by 5" you are referring to blade length.)
For example, this week with cold weather upon us, I carried a smallish Charlie May "Trace" (Scandi edge) in a leather sheath. This knife has a 3" blade though much wider than a slippie.
The advantage is that I can get a better grip and the knife can take a lot more potential abuse, both of which are positives if the knife has to be deployed and used with cold hands/fingers when motor function and coordination are not at their peak.
With a bit of improvisation there isn't much you can't do with a
small fixed blade knife to augment your slippie. (Batoning, fire starting etc etc)