This is getting off-topic, but I disagree.
The thing is, the PHB is not nearly that clear cut - as far as I understand it, both interpretation are possible.
The Warlock could be a Pact Mage or s/he could be a pseudo-cleric.
There is no rule that a Warlock loses anything from killing their patron. I am not even sure it is the same for every warlock.
Even what is offered to the patron is left vague. Sure most people think of the classical "selling the soul", but it is not really stated.
And, at least in Ferûn, your soul should either be sold or you should worship someone who is interested in you, otherwise you end up as a snack for Asmodeus (I think).
Which actually begs the question, why would any patreon give you an increasing amount of power, or even keep teaching you, if they already have your soul?
Bottom line, the warlocks nature is not quite as obvious or clear cut as many seem to think.
