easy there champ. Its not bullshit. If a source gives you 90% purity on one order, and 50% purity on another order. Then they aren't what I would consider a "good" source, and I would move on and try to find another source.
And it is absolutely the raw suppliers fault, its their responsibility to deliver what they advertise...if you received shit powder from a source, would you just say "its okay, its not your fault, you didn't know what you were selling, I dont mind that you just ripped me off" ??? Hell no you wouldn't! youd raise hell, try and get the source to remedy the situation, and then never do business with them again.
I agree that 90+% of powder sources are going to be inconsistent, but thats not really the point of my post (which you clearly missed) my point was the money spent finding a GOOD supplier will pay off in the long run.
You made some assumptions about my post that were inaccurate, try not to jump to conclusions, its not a good look