You put it better than I myself had formulated it in my head yet, why I am weary of those rumours. I find similar arguments here in Europe, where our fascist movements, which are without a doubt supported by Russia, are then sometimes reduced to being some sort of wholly foreign influence, instead of admitting that Russia is stoking flames in embers that had always been part of us and the problems we face.
The fields which are being harvested by both external adversaries and power hungry ethics-free insiders were plowed, fertilized and sowed by 4 decades of exposure to the style of disinformation favored by Neoliberalism whilst the consequences of its policies were getting more and more felt by the average person, IMHO.
When your belt keeps tightening, what you can buy with the income from working keeps being less and less and life feels more and more like swimming against the tide, all the while the authoritative figures of old (mainly the Press and mainstream party politicians) keep telling you that things are getting better (“the GDP is growing!”), eventually people lose trust in said authoritative figures and those with a similar style of discourse, which opens the door to non-mainstream political voices with a different style of discourse (including populists), and very wealthy people aren’t going to be funding Leftwing parties whose ideas are not shaped by Neoliberalism, to fill the political gap opened by the general loss of trust on the mainstream, they’re going to be funding Rightwing voices who blame the powerless for the ills of the nation rather than those very wealthy people who have been pillaging it for decades.
