I'm not positive, but I think it's from the laws regarding reporting of campaign donations. I don't know that it's scary that it's available online, because I'd bet it's available by simply requesting it or going to your local library, but putting their actual addresses online I don't agree with. Make 'em do the work to find out an address, or simply give a name without attaching an address.
There's a guy near me who runs a publishing company that used to keep me employed at a printing company near me.....now, I knew his leanings before this, knew where his offices were, and knew where his house was, but had I not known this, it's darn near impossible to tell there's an actual house on the lot where he is, and who lives there.