> That problem occurs in exactly the same way on any vote in a "normal" parliament where party affiliation determines vote.

It also occurs under most 'normal' voting systems in safe seats.

Lobbyists have power through money and networks. If a non-pivotal voter has power, it's likewise through something else than his vote.

That this is a problem with party whipping in parliaments too, doesn't mean it's not a problem.

I'm not sure party whipping is actually a problem?

Btw, parties and how they work in specific electoral systems are (at least partially) a function of how general voting works in those systems.

If you have a sortition system, parties might work rather differently, if they would be present at all. MPs submit to the whip's party discipline, because they need the resources of the party to get re-elected etc. Under sortition, the incentives are all different.