There is no such thing as a last resort in an EFATO. You make a decision based on the info you have. Turning back may well be appropriate in a certain case, but by having stupid catch all phrases we could put an element of doubt just where it really isn't needed.
Most of the time turning back isn't appropriate, however, that is absolutely not true in every potential circumstance and that's why phrases such as "never do this or that" should be taken out and beaten to death with sticks.