Meanwhile, the Senate and the Presidency are controlled by Republicans, and gerrymandering is utterly irrelevant to those outcomes.
You're correct that at the first order gerrymandering is irrelevant to the Senate and Presidency. Gerrymandering comes into play as a second-order effect, though; when used at the state level, it can cause state legislatures to effectively lock to a party. These state legislatures can then make changes to the way voting is organized in their state, enfranchising and disenfranchising voters in ways that support their party, and funding/defunding polling districts per the same. This has an effect that can be plenty large enough to swing statewide elections: see the last election's shenanigans in South Carolina, Georgia, and Florida if you're in doubt.
You said "explain your reasoning", and that's what I did.
No need to get defensive over it and try to pretend like it's irrelevant to the discussion. This is literally the discussion you explicitly asked for. If you don't like the fact that the Republican party has acted in a decades-long effort to guarantee their own power in perpetuity with or without public support, don't get mad at me, get mad at them.
I never disputed Republicans’ attempt to give themselves an electoral advantage. I just disagree that this is consequential, much less decisive. As you yourself argued elsewhere in the thread, NC Republicans’ chicanery could mean a 2% swing in the House. Not to put too fine a point on it, but you’re telling me that by attributing 100% of R success to trickery, in a state that’s the worst of the worst in this regard and so yields the biggest effect size, you can create a counterfactual where Democrats have 2% more seats in just one half of Congress?
Your smoking gun is a rounding error. So I’m asking again: how do these sorts of numbers lead you to believe what you apparently believe?
In any event, the House sits beside the Senate and the Executive. As another commenter pointed out, this case at best explains ~2% of the dynamics of one out of three legislative bodies offices. And sure, other states might contribute a bit more. Fine, maybe it clears my 1% threshold; but just barely.
I'm not here to defend Republicans (I think they're pretty bad) or the practices you described (I also think those are bad). But that doesn't change the fact that gerrymandering and power grabs and Fox News are nearly completely inconsequential in explaining the world in front of us. Quit with the liberal wishcasting. People don't vote Republican because they've been misled by some sinister conspiracy. They just don't want what you're selling.