Why does it exist when you're still working on its race when it doesn't have to exist as a creature when you're working on its feats, which (as you say) come afterward?
It exists in rules, as a viable complete statblock through each. In plot, it does not exist until inserted. The two are entirely separate.
And where is it said that a requirement for taking an inherited template is that you not have an acquired template?
The requirement is "always part of a creature's existence." If that is not met, it cannot be applied.
"Now it's a Skeleton Kobold so you can't apply Half-Dragon" is a valid objection because now it's an actual creature, then "Now it's a Kobold so you can't apply Half-Dragon" should be, too. Which is obviously ridiculous.
Honestly, I am beginning to think you are being intentionally dense. You may as well be arguing that the type pyramid does not apply, or that there is no order of operations involved in creating characters at all.
When creating characters or monsters, in the time you are defining race, you have certain options. One of those is to add inherited and acquired templates. The wording of the two not only implies a logical need for the one to be first, but also states that the creature being made cannot exist for any amount of time without it's inherited templates. This is, honestly, a bit ambiguous, but fortunately there is a perfectly logical conclusion that clarifies it without changing meaning in the least.
Or you could create a contradiction in which the creature has potential to exist without the inherited template while still later being a creature with inherited templates.
This is not a problem for base races, as they exist without templates at all. But once you start adding templates, there is a time where it has templates applied but does not have it's inherited templates, which is explicitly disallowed.
Any exceptions, such as savage progression levels or classes that grant templates, are all explicit exceptions and thusly trump the general.
Although mobs are treated as one creature...
Although means that "treated as one creature" is the general case, because you're setting up all their non-single creature attributes as exceptions to that.
Again, there is nothing that defines mobs as a single creature. Simply that, "similar to a swarm" they are treated as one. This is why I continue to point out the difference between a mob and a swarm. Swarms are explicitly defined as a single creature. In fact, "a swarm is defined as a single creature" is a direct quote.
No such quote exists for a mob. It is multiple creatures acting as one for very specific purposes. This means that, by default, it is still multiple creatures
except as specifically noted in the template.
The fact that they clarify how this interacts in one specific regard does not mean everything else defaults to "a mob is one single creature."
Because those are not the mob rules.
Mobs are
never defined as a singular entity. It is merely "treated" as such for the things the template lists.
But as I said earlier, none of this really matters to the build at hand. But if you would like to continue these asides, I would be happy to respond in another thread if you PMed me a link.