I’ll grant you that Clinton’s allegations are less “far-fetched” than Trump’s. But that shouldn’t be the standard! We shouldn’t be trying to draw distinctions over claims that are totally made up and ones that are only mostly made up.
To use a legal analogy, I don’t see political discourse as being something where there should be judges excluding unreliable or prejudicial materials. Information is fair game.
I was against impeachment (I still think it was stupid), because it was a political stunt with no hope of actually removing the president. But just morally, Trump richly deserved investigation. "Where's there's smoke, there's fire", and Trump's campaign and administration put out a burning oil well's worth of smoke. He lost his National Security Advisor to a foreign agent violation within weeks of taking over. Senior members of his campaign coordinated with Julian Assange. I don't think you can pretend like this was all fake.
(Just to calibrate: I also think Clinton should have been impeached).
Of course it's not clear if Hilary would have won if there was no such interference, but her claim is not nearly as far-fetched as all the baseless crazy batshit stuff being thrown around by republicans nowadays.