There is a lot of merit to what you say, but don't you think that Trumpism is more insular than typical partisan allegiance in the past? I say that for several reasons, including:
-- Trump, himself, does not accept disloyalty. Fauci has been a notable exception, but otherwise as soon as Trump perceives that an official is not going to support 100 % of what Trump says, or might have even a slightly different take on things, that person is ousted.
-- Similarly, Trump supporters are markedly more inclined than past partisan examples to be absolutely intolerable of dissent. Look at the long list of well-respected Republicans who dared voice a significant difference of opinion. As you noted, they can lose connections. But this is worse. They are immediately ostracized, threatened, etc.
-- the notable banding of Trump's support. He has a particular base. It does not grow much, statistically speaking, when things are going well. But neither does it shrink much, if at all. This supports the notion of a singular identity when it comes to Trump, which yet again mirrors his management style. You are either unquestioning and all in on him, or you are out.