You are correct. Ingestion will screw up even the most experienced and relegate them to babbling fools looking for a place to hide.
Only fools eat the stuff.
The problem with eating it is that, first, you don't know the dose, and second, it takes a while to feel the effects. Smoking it, you see the dose and feel the effects more or less instantly and it's more or less controllable. Eating it, some people eat too much to start with because they have no reference to the potency, then when they don't feel anything 45 minutes later (or even more--a full stomach slows the uptake), they eat more. Then, two hours later, they are the babbling fools you describe. But homicidal, I don't think so.