Perhaps you misunderstood: I was not pushing a particular interpretation, merely pointing out that that what we observe is compatible with an alternative one (and of course, many others). I agree with you about selection bias, unobservables, etc.
That could of course happen (and, to be pedantic, one could equally well argue that it is happening because of any other language feature/change, since we are truly talking about unobservables).
Arguments about language adaptation, especially counterfactual/hypothetical claims, usually have limited value. Which is why I think it is best to approach this decision from a technical/language design perspective.