I can't argue with your anticipatory eulogy for the post office. The cyber age is surely its death knell. Whether or not Congress, no matter which party controls it, will surrender its constitutional power to establish mail service is another matter.
I went to college at a place famous for producing politicians. Several of my roommates comtemplated political careers after graduation and one even ran for Congress (and lost). When I talked to him about the experience he provided two unforgettable insights; the first was the absolute necessity for any successful office holder to lie repeatedly. As a native westerner transplanted to East for high school and college, he had adopted most of the social values of his contemporaries. But he wasn't going to have any chance in his congressional district as anything of other than a gung ho gun advocate. The second was the relentless driving force of money in politics, and how he spent most of his campaign time and effort fund raising. Since he hated begging for money from strangers, it was clear to him that a career as an office holder wasn't meant to be, and he happily moved on tort law.
Politics on both sides of the aisle selects for folks willing to say things and do things that you and I would simply never accept.
It sounds like I'm making your argument about limiting government for you. If only those who argue so passionately in favor of limited government really believed what they say. More likely they're just in favor of their own set of pigs at the trough.