[@Rune_Alchemist]
Okay, let me put this in a different perspective.
You have a fire slayer.
You have an air slayer.
You have an ice slayer.
You have a sound slayer.
You have a poison slayer.
You have an earth slayer.

Now, that's six different magics that are going to be useless.

Now add in the fact that some slayers can eat secondary elements.
That's six more elements that are useless. See where I'm going with this? They're inherently more powerful than other magic because they can just eat magic that is thrown at them, with a few rare exceptions.

So, assume we can think up plenty of challenges for these slayers. It still doesn't change the fact that Dragon Slayers are rare. God slayers are rarer, and Demon Slayers even rarer. So, tell me how we would have a guild 'primarily made up of slayers'? This is AU, so yes, there will be a little more wiggle room with stuff, but I don't want a million slayers, because this isn't canon breaking fan fiction.
I'll also point out, I never once said the guild was made of primarily slayers. What I said was it was guild known for having 'multiple' slayers.