It's pretty simple but I can fill in a what for that bold bit. Don't think too hard on it, there probably wasn't too much thinking involved. Back before
this call for a survey brigade killed the long rest warlock one of the 5.24 goals was to normalize class/subclass level contributions so subclass was always at 3 and you could just make a level X feature and know what kinda thing it was swapping out regardless of class.
Among those discussions there was a common exchange that went something like "
what would that look like" -> "
probably a lot like a drug dealer where the first hit's free". Sometimes that was a question about fluff with a bad answer about fluff and
often it was question about fluff or mechanics with answer about mechanics. Crawford even mentioned something along that first taste is free in one of the
many 5.24 warlock videos. That exchange spotlights a solution for your "what were they thinking" question that makes it easily answered with something dismissive like


"
context of the retort is irrelevant and there's no meaningful distinction between discussion of mechanics and fluff and talk about mechanics is totally 1:1 transferrable to fluff because rulings not rules & flavor is free".

.