Why? So that it would be easier to communicate the abrupt shift in the right wing of American politics over the last 30-40 years or so. Just a few decades ago, Barry Goldwater would've been considered "far-right" --- and he was pro-gay rights, personally against abortion but pro-choice, and held many views which, today, are considered "liberal extremist" by anyone in even the remote right wing. Now, a children's movie with an environmental message has been dubbed outright "liberal propaganda" by the right wing (and this is fairly warm on the heels of the accusation that Sesame Street is "racist" and "liberally biased" because it is targeted towards an audience of low-income families that may not have reading materials readily available for children).
And when you look at this effort to classify America as a "Christian nation," and you hear Sarah Palin say that the founding fathers put "Under God" in the pledge, and you see people point to "in god we trust" on the money (right next to "Novus Ordo Seclorum," for extra irony points), and you hear people like David Barton say things like, "see, all this evidence of us being a Christian nation just goes to show that we've been using the same time-tested "conservative" values system since the dawn of America, it's just these atheist liberals who are trying to suddenly change everything," you realize....it's one big fucking lie. Just 30 years ago, "conservatives" were something completely different from the ones we see today. These people are equivocating between two completely different *meanings* of the word "conservative" -- another good example, when (Republican) Eisenhower was president, he said that any party which tried to destroy social security would not be heard from again in our nation's political history (i.e. they would die out), because they do not represent the interests of the people:
Should any political party attempt to abolish social security, unemployment insurance, and eliminate labor laws and farm programs, you would not hear of that party again in our political history. There is a tiny splinter group, of course, that believes you can do these things. Among them are H. L. Hunt (you possibly know his background), a few other Texas oil millionaires, and an occasional politician or business man from other areas. Their number is negligible and they are stupid.
--President Dwight D. Eisenhower, l952
And yet, what is the main economic effort of the GOP in stabilizing the budget today? Gutting social security, under the guise that, "well, we already 'borrowed' all of the money from it to give tax breaks to the top 1%, so we might as well just get rid of it, it's just too much of a 'hassle' to pay back all those taxpayers we're basically trying to defraud."
And so now, we're left with a party that, in an attempt to reconcile the rapidly-changing political sphere of the last 40 or so years with their nostalgia-laden delusions that "everything was fine before these damn libs came along," has rather suddenly taken upon itself the task of sifting through history and re-labeling anything that doesn't agree with this "new conservatism" as "liberal propaganda." For the record, "The Lorax" by Dr. Seuss was first published in 1971. 1971, people. And only now, with a movie release on the horizon, is it considered "liberal propaganda" by FOX News. Because it has only recently come to be that environmentalism is an anti-conservatism, anti-GOP standpoint.
The saying is supposed to be that you learn from the past to shape the future, not change the past to control the future. I guess today's fragmented GOP really won't ever learn.