1 point
I don’t know that that’s true, there can be other cultural reasons.
In Hindu-based cultures you wouldn’t eat cow, as in largely Muslim ones you wouldn’t eat pork.
Eating horse is common in a lot of countries despite falling into your “useful enough not to kill” category. Sheep are useful for wool production but people still eat lamb.
Rat is easy to domesticate and they are frankly useless at drawing a plough but eating them is still taboo in many places. A couple of billion people eat insects daily, but there are still many other countries where it is very rare to eat them at all despite the ease of farming.