I think what this shows is that there’s a perceived problem with the Democratic Party. Democratic Party policies are often popular on their own (see the numerous Medicaid referendums), but the party’s candidates aren’t. I’d assume that this comes from a lot of socially conservative and economically liberal voters who value social conservatism over economic liberalism.
FWIW I think there's a whole host of Conservative ballot measures that could pass; I know it was quite different back then but California was willing to elect democratic senators & strong majorities while passing ballot measures that were quite conservative
Oh, absolutely. Things like the Death Penalty for example. We kept it and tried to streamline it in 2018 (or 2016? Can’t remember off the top of my head).
The key is that negative partisanship operates at the party level. If you take a no-name candidate and tell people their party, 40+% of voters will automatically have a negative perception of that candidate because they associate a suite of hot-button issues with the candidate. When you adopt the party label, most voters are going to assume you back those issues (and typically you do).
Even issues that are ostensibly partisan don't really cut across people's political identities the way that a political party will. Parties bundle issues together; ballot measures on single issues give voters a lot more wiggle room.
With that said, I actually can't think of very many conservative ballot measures that will outrun a Republican candidate. First thing that came to mind was the Nebraska death penalty repeal, but actually the vote against repeal only outran Trump by about 2 points.
The gay marriage amendments from last decade are a good example. They typically outran the GOP because minority voters have views on social issues roughly similar to the distribution among whites, it's just they won't vote for the GOP because of perceived racism/nativism by association. African Americans, motivated by the communally important AA churches, certainly went for these amendments.
Another example often seen at the local level is commuter transit expansion and development. You could say it's NIMBYism, but those voting against it are often wealthy who would be aligned with the conservatives if not for various things they associate the GOP with.
Potential conservative issues that could see similar success at the ballot are The Right to Die, decriminalization of dangerous drugs, and anything related to bodily or genetic modification if we ever get that technology.
