Why do some manufacturers reverse preamp polarity in the first place?

Here is all you need to know about polarity. 
http://www.6moons.com/industryfeatures/polarity/polarity.html

Cheers. 

I get an uncomfortable feeling when the 6 Moons author states, “there’s a 50-50 chance a given recording features Inverted Polarity.” I’m mean how does he know?” I would sincerely like to see someone, anyone, compile a list of say fifty audiophile recordings, LP and CD, with Polarity for each. That doesn’t seem too difficult. So far all we have is George Louis’ Polarity List. Which is great that he compiled that long list, but I have trouble buying into it, primarily because he concludes the percentage of CDs that are in Reverse Polarity is so high. But 50-50 assumes no audio engineers or mastering engineers check for Polarity and I don’t buy it. I’m not saying it’s impossible, just the probability is low.

in some pre-amps that contain a phono stage (or in a separate phono amp), that stage (or amp) may be of inverted polarity while the line stage is not (or visa versa). What are you gonna do, reverse your speaker leads depending on whether you are listening to an LP or CD?

Invert the phono cartridge leads!

But 50-50 assumes no audio engineers or mastering engineers check for Polarity and I don’t buy it. I’m not saying it’s impossible, just the probability is low.

Recording engineers in fact do not check for polarity. For the most part they regard polarity as so much hand waving. So 50% of all recordings having reverse polarity is correct.

Really? The Polarity pundit claims 92% of CDs are in Reverse Polarity. And he has a Polarity List to back it up. Furthermore the Polarity Pundit claims entire record labels are in Reverse Polarity. What evidence do you have? Who is right? I await your evidence.