While I think at the broader level you are correct in mechanism I'm unconvinced that this is how it works in reality. There are too many examples of ideas spreading like wildfire far faster than people die out. Ideas that people hold with high passion. An example might be same-sex marriage where we see a larger rate of increase in support post legalization[0]. While younger generations have higher initial support, all generations increase in their support. 30% in the 00's and 60% today for the 55+ age group. That can't be due to the transfer of 35-55's because their baseline was only 40% in the 00's.

Remember that Dawkins use the analogy of a virus, not of an inheritable disease. Certainly you are correct in part as there are analogies to inheritable diseases with thought but it's also important to remember how quickly these mutate and that the mutation does not occur at inheritance like this is a game of telephone (in some way it is, but I hope that was clear). Moreso, things are mutating faster than ever. Religion is a great example of this, as it is a highly inheritable belief, yet the rate at which interpretations of a religious text has changed has changed much quicker than before. That's because, unsurprisingly, the interpretations are a reflection of ourselves and our times are changing faster than ever.

I don't know how old you are, but I do remember a time before Fox news and before the 24hr news cycle. They first took off around 9/11 and then gained many more during the financial crisis. I grew up in a Fox family and unlike my many liberal friends (which I am undoubtedly left), I will occasionally watch such shows like Bill O'Riley, Hanity, or Tucker. Why? Because they are well scripted programs that exploit the aforementioned principles. It helps me prepare for the nonsense my dad says during holidays. There's two points here which I'll rely on inference for as I'm already writing a lot. The first is about how they can rapidly change long held beliefs (e.g. Russians are the bad guys) and the second is about how this exercise let's me interrupt my dad (and uncle and BIL) and tell them exactly what they are about to say.

Everyone can be manipulated, including you and me. We're being constantly manipulated and not always by intentional forces (more often unintentionally). Dawkin's viral theory is a great place to start but like viruses you have to understand that there's a much more complex and intricate system involved that creates a large array of effects and you're not wrong that there are both genetic and environmental predisposition that makes a virus worse for some than others. But the same goes for the reproduction rate as well as mutation rate. The truth is that you can convince fundies that the Earth is old. I know this because I am an example. I know this because the rate of people like me is not just increasing, but accelerating. Apples fall a lot further from the tree than they used to, not because the laws of physics changed, but because the geography did. So either you believe that I'm (and others) are an exception to the rule or that there is an underlying mechanism that allows this to happen. The former does not have explanatory power for the increase, let alone the acceleration.

[0] https://news.gallup.com/poll/350486/record-high-support-same...