Sure in principle, a (US or UK) referendum process would have to be safeguarded, if all the other legs of healthy democracy were still in place, and the (US) judiciary hadn't already in 2010 removed the mechanism by which excessive money coud be kept out of politics, but that's all well in the rear-view mirror.
I think your analysis is wanting to hang everything on some structurally independent mechanism that will persist longterm, regardless whether it's a referendum mechanism or rule of law + independent media.
> At the state level, you still defend your values with one person one vote.
No you can't do that either, because only a few (27+16 / 438) Congressional districts in 2024 were toss-up/competitive and not safe/gerrymandered, per Brennan/Cook Political Report [2]. And when one party establishes a quadrifecta in a state, they try to lock down that numerical advantage for another decade or two.
[0]: "U.S. Debt Is on Pace to Set a Record High, Going All the Way Back to 1790" https://www.nytimes.com/2025/05/20/upshot/record-debt-republ...
[1]: https://www.youtube.com/watch?v=qEJ4hkpQW8E
[2]: https://www.brennancenter.org/our-work/analysis-opinion/comp...