system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why does everyone say the killing curse is unblockable when it clearly is blockable?

Seriously. 

1: You can just conjure a physical object to block it. 

2: It can be blocked by sacrificial love magic. Which would indicate that there are other forms of magic that can block it, just no one has researched it.

3: It probably doesn't work against magical creatures like Dragons/ Chimera. Otherwise they wouldn't be considered such a threat if any wizard with the stomach to throw an AK would be able to one shot them.


So does "not blockable" mean "not blockable with a protego (along with lots of other nasty spells), but blockable by physical objects, obscure love magic and dangerous magical creatures"

Because that doesn't quite roll off the tongue as well.
gpt
For one, the only people who really talk about *avada kedavra* being unblockable are those who would face it in combat: aurors, and the Order of the Phoenix. Members of these groups are trained at magical combat, but the Killing Curse can't be blocked *by the spells that they most commonly use to defend themselves*.

Wizards, on the whole, aren't that smart, nor are they particularly adaptable to new information. They've been trained to react to a flashing ball of light streaking toward their face in very particular ways. Most aurors or Phoenixen have a single spell as their go-to. But if they're fighting someone who uses *avada kedavra*, that spell *will not work*.

"You can't block *avada kedavra* is a simple, catchy phrase that will stick in their minds and hopefully prevent them from getting killed in the opening exchange.

As for the sacrificial love thing, there are what, two or three people in the entire world that understand the mechanics of that?

And dragons may or may not be susceptible to *avada kedavra*, but even if they are, most wizards *don't* have the stomach to use it, even in self defense, even against a non-human. Hermione and her class were appalled when Barty Crouch Jr (posing as Alastor Moody) used *crucio* on a *spider*.