A few notes comparing the present with the past, and trying to draw conclusions...
[1] The medieval church as a propagandist system. As fas as I know (I'm basing this on Joseph McCabe, who rebelled against Catholicism) the work medieval monks carried out, in whatever their word was for studios for inventing and copying books, seems to be rather similar to that of the modern media and BBC and the Jews who controlled the USSR. There were hagiographies - biographies of 'saints' and others, attributing all kinds of magical powers to them - such as floating across the Irish sea on tombstones. And accounts of victories over enemies. And of course accounts of 'martyrs'. McCabe states that nobody these days even bothers with the content of these productions; in a similar way the output of media people during (for example) the First World War or Vietnam War is pretty much ignored.
[2] Greater multiplicity of modern belief systems. Since say 1200, parts of the world have grown richer and the technologies of information have grown enormously more widespread and impressive. Richer countries, and population increases, both make possible more and more 'knowledge islands'. Protestantism is an obvious example of fission and invention of new systems, but Catholicism too had many local (usually national) variants. Most of these belief systems are now more-or-less ignored; how many people know what 'paedo-baptists' are, or what the 'Great Schism' was about? The rise of science obviously permitted elaborate new sets and subsets of information and it's noticeable that many money-making systems have been invented in the USA - Mormons, Christian Scientists, Scientologists, Seventh-Day Adventists, Jehovah's Witnesses etc etc.
[3] There must be more or less Darwinian rules of competition between groups. Assuming all societies can support in a general sense (money, resources, manpower) only a certain amount of irrational or unimportant activity, there must be upper limits to such activity groups before they arouse opposition or conflict, either with the general population, or with other ideas-based groups. Thus in 19th-century Britain there was conflict between assorted groups new and old - Presbyterians, Quakers, Primitive Methodists, Congregationalists, Ebenezer chapels etc - and Anglicans. In the last 50 years, some science frauds known to me seem to have been (in date order) nuclear science, NASA, AIDS, Climate 'science'. Throughout this period there has been a rather undatable tendency for much of biology to ignore control experiments, and construct elaborate wrong theories - which extend over everything from drug action to vaccination. Obviously, in principle, all these groups compete for money. There must also have been an immense amount of military-industrial corruption and fraud. There are also science-like groups, believers in a range of weird things, which seem fuelled by most peoples' inability to understand science.
[4] There's a specific 'Jewish' component in modern times which has become increasingly important, like Islam. For example, Einstein, Marx, Freud, Boas, Wilhelm Reich, Sartre, Chomsky, Derrida and various hangers-on have invented or modified many more-or-less absurd theories. They've also introduced systematic distortions, for example relating to the USSR and Germany. All of these must follow Darwinian rules, and have or had opposition, with, as yet, uncertain results.
[5] Most 'revisionist' types are one-topic people. I'm unsure why this should be. On the face of it, sudden awareness of some fraud might be expected to prompt people to examine other wrong beliefs they held at one time. In fact, most don't. I could list a number of examples known to me personally, but to save time I won't.
[6] Because of [5], much critical work and many attacks on belief systems are ineffective. The sort of thing I have in mind is Dawkins' attacks on God. Dawkins carries with him an immense amount of baggage - for example, (i) claiming to believe in relativity, while simultaneously regarding many Christian beliefs as obviously absurd; it's not credible to me that Dawkins can properly understand relativity - it's just a fashion to pretend to believe in it; (ii) Dawkins' not understanding that tribal and racial belief systems, such as Islam and Judaism, do not have the optional aspect - take it or leave it - that Christianity has; (iii) assuming the official versions of such events as the First World War, the Cold War, the Vietnam War, are honest and accurate; (iv) Dawkins doesn't appreciate that defects in modern biology mean that some claims by creationists are in fact correct.
[7] History as a guide? Obviously, history has the great advantage of being empirically verified, rather than being some theoretical construction. Or at least it should be; unfortunately, one lesson from history is that most historians are not very competent. Aspects of the past that suggest themselves as being worth study are: (i) The way bodies of theory lose importance. The obvious example is the Reformation, but its obviousness hides vast numbers of less important examples. (ii) The psychology of attack on wrong beliefs: there are two obvious subdivisions - one is the overview, bringing in many coherent arguments without going into tedious detail; the other is in depth, minute research. 'Holocaust' revisionism illustrates both of these - 'Did Six Million Really Die?' is a brilliant quite brief overview, while many monographs on topics such as 'gas chambers', cyanide, and the Nuremberg Trials illustrate the necessary in-depth work. (ii) Information control - such subjects as 'hoax maintenance', control of media, use of violence. (iv) Studies of actual topics in detail, where possible checking that myths haven't been thoughtlessly carried over. (v) Studies of suppressed topics, lost through deliberate suppression - mass murders in Moghul India, in the Belgian Congo, in Armenia and the in USSR, illustrate the sort of thing.
This sort of thing is what I consider 'revisionism' to be. It's a new subject.