[dragonwriter]

> Are the counterexamples offered by the theorem pathological, in the sense that they are unlikely to occur in practice but are theoretically possible? Or would they arise in practice frequently using standard rank voting systems?

Which particular problems occur, and the frequency with which they occur, depend on the particular voting system.

Plurality and majority/runoff (which are ranked preference voting systems with a vary narrow constraint on the preferences that are expressed on the input ballots, which is pretty much the same constraint as on the preferences reflected in the output of any single-winner voting system) hits problems fairly frequently in practice, but most of the common voting systems that most people think of as ranked-preference systems (IRV, etc.) still hit them in practice as well, though not generally as frequently and in ways which create as clear incentives to tactical voting.