Republicans won the Congressional Popular vote exactly half the time since then: 2010 (by almost 7 points), 2014 (by almost 6), 2016, and 2022.
As long as we are talking about counter-factual political systems: If the US had a parliamentary system like most democracies, Republicans would have controlled the presidency for 8 of the last 16 years. Given their coalition of disaffected minorities and recent immigrants, Democrats benefit tremendously from the quirks of the US Presidential system, which lends itself to nationwide machine politics.
One of these complaints, that Republicans benefit from the structural tilt away from densely populated states, is objective. The other, your argument that Democrats reliance on immigrants enables machine politics, is subjective. They aren't directly comparable arguments; the latter argument feels like special pleading.
I understand the “structural tilt away from densely populated states” to be a different thing than gerrymandering. Whichever party outperforms in sparely populated rural states (historically, it was democrats) has an advantage under the US system.
The point that directly elected executives give rise to different political dynamics is no less objective. Among those political dynamics is the feasibility of blasting a nationwide message that embodies the party in a person low information voters can relate to. That’s been a major enabler of Democratic machine politics aimed at immigrants. And these days, it’s an enabler of MAGA machine politics.
It’s quite different in Westminster style parliamentary statements, where people in different districts vote for different candidates.
Yes, that’s why OP cited the Congressional popular vote. What’s happening is that both parties gerrymander, so it largely cancels out. For example in Maryland, democrats won 65% of the 2022 Congressional popular vote, but hold 87.5% of the House seats. The 450,000 or so excess Republican votes—votes for republicans which didn’t contribute to a Republican house seat—cancels out some excess Democratic votes in Montana or Wyoming.
You can speculate about such factors, but the House popular vote tends to line up pretty well with opinion polling of the "generic Congressional ballot"--which is a nationwide measure that isn't affected by gerrymandering. For example, republicans were leading by up to 10 points in polling in 2010 before they ultimately won by 7 points: https://news.gallup.com/poll/142718/gop-unprecedented-lead-g....
As long as we are talking about counter-factual political systems: If the US had a parliamentary system like most democracies, Republicans would have controlled the presidency for 8 of the last 16 years. Given their coalition of disaffected minorities and recent immigrants, Democrats benefit tremendously from the quirks of the US Presidential system, which lends itself to nationwide machine politics.