Let’s say you get to cast 3 votes, and that I’m a corrupt politician. I’d put an issue that you care deeply about on the ballot with 3 other issues that you’re likely to care about. If I can engineer a ballot with 4 issues that you really care about, but only 3 issues that my coalition cares about, we can concentrate our votes while you’re splitting yours, and we win all 3 of the ones we deem important.
Sounds like the perfect opportunity for the media to run one-sided stories about how much support there is for one issue or another, to scare people into opposing it. You don’t know how many people voted for an issue until it’s too late to cast your own vote.