Bingo. Chloroform fell out of favor as an anesthetic because the gap between the lower limit/ therapeutic effects and the upper limit/adverse effects is very small. Even during the mid-late 1800's when chloroform was given with specialized masks and careful dosage from doctors, about 1-in-1000 people anesthetized with it would drop dead from cardiac arrhythmia. If you have a large blob of it on a handkerchief and it's strong enough to knock someone out, they're probably not waking back up.
Also, today-I-found-out that the trope of it being a "magic knock-out drug used by criminals" (despite it being slow-acting IRL) goes back to at least 1865, as debunked in a The Lancet medical journal from that year: