Most of this post is meant to offer a solution to this specific criticism of Party List that points towards Asset as a superior simple PR method.
Apparentment is when parties can fuse the votes over the quota they got for their lists into a “super-list” in an attempt to get more representation i.e. a party gets 1.4 of a quota and can’t use that 0.4 of a quota to elect anyone, but if they have made an alliance with another party that got 1.6 of a quota, they can combine their surpluses to elect a representative that they agreed on before the election.
Why not do it with candidates?
Candidates could run independently, but if they don’t get a quota of votes, they could come up with several layers of apparentments, culminating with the party list and any electoral alliances their parties have made. It would probably look something like Candidate>Couple of candidates that agree on an issue>Subfaction>Larger subfaction>Party/Faction>Party’s Electoral Alliance with other Parties>Etc. Unlike Asset, all of the negotiations are handled pre-election, and it might even be possible to allow a voter to decide how many layers of apparentment they want their vote to travel down before exhaustion (or simply exhaust the vote if their candidate can’t win a quota of their own before any apparentments have been activated.) Allowing a candidate to choose what % or how many of their votes should go to particular apparentments (or even putting conditions on how the votes flow, so long as it doesn’t freeze the algorithm) might be a further improvement.
This could be criticized as being byzantine, but candidate negotiations don’t seem very transparent either. It is, at the very least, precinct-summable and based on choose-one voting.
I’d also wonder if something like this can be used to give a majority-winning coalition a few backup seats in case some of their representatives vacate their posts i.e. parties form a mega-alliance before the election, and if the parties in that alliance collectively get a majority, then they can use the backup list in case a representatives from one of those parties has to vacate. It’s possible to require the consent of the legislature to do this, as well as perhaps allowing several electoral coalitions to form backup lists, with the legislature getting to decide which coalition and which list to honor in case one of the parties in that coalition has a vacancy.