Well, the second problem would be figuring out who curates the system. If you've ever voted on a referendum you'll probably know what I'm talking about. You can make any proposal sound awesome/horrible if you leave out the right details.

If you've ever organized to resist a referendum you've probably also experienced the "we'll just rephrase this and try again later" effect, wherein special interests just need to stubbornly keep pushing until the opposition voters get sick of participating in the polls.

I don't think these are unsolvable problems, but they do inherently require setting up a representative beaurocracy of unelected technocrats -- an apparent oxymoron. It's gotta be someone's job to run the machine and ideally you want them to be looking out for the people above all else.

So, how to play kingmaker? Well, if we take literal kings & elected representatives off the table, what remains is a model akin to academia, wherein credentials & seniority are prioritized above most else. It's not a bulletproof system (none are), but if you squint hard enough the EU sort of exemplifies what this model could look like -- just replace the delegates with smartphones, essentially.