When your doctor points to the chart and asks you to rate your pain from 0 to 5, does your answer mean anything? In a way, yes: the more pain you are in the higher number you will report. So if last week you were 2 and this week you are 3 then she knows you are in more pain this week than last.
But she also wants to know your absolute level of pain and for that purpose the usefulness of the numerical scale is far less clear. Its unlikely that your 3 is equal in terms of painfulness to the next guy’s 3. And words wouldn’t seem to do much better. Language is just too high-level and abstract to communicate the intensity of experience.
But communication is possible. If you have driven a nail through your finger and you want to convey to someone how much pain you are in that is quite simple. All you need is a hammer and a second nail. The “speaker” can recreate the precise sensation within the listener.
Actual mutilation can be avoided if the listener has a memory of such an experience and somehow the speaker can tap into that memory. But not like this: “You remember how painful that was?” ”Oh yes, that was a 4.” Instead, like this: “You remember what that felt like?” “OUCH!”
Memories of pain are more than descriptions of events. Recalling them relives the experience. And when someone who cares about you needs to know how much help you need, actually feeling how you feel is more informative than hearing a description of how you feel.
So words are at best unnecessary for that kind of communication, at worst they get in the way. All we need is some signal and some understanding of how that signal should map to a physical reaction in the “listener.” If sending that signal is a hard-wired response it’s less manipulable than speech.
Which is not to say that manipulation of empathy is altogether undesirable. Most of what entertains us exists precisely because our empathy-receptors are so easily manipulated.