They are not legitimate concerns though. Basing the games credibility off of thoery crafting isnt reasonable. Now had those people actually played against it and thought it was "OP", then the opionion would have merit.
I have, among others, given plenty of reason to allow 30k im our events locally. The fact of the matter is, 30k is so underpowered vs current things in 40k that any argument against is just plain silly.