It does, but that's essentially the point of fixing #638. Rebuilding objects for every test isn't something we can do for any other datapoint source (either fields or multi-point methods), and inconsistent behaviour between these has its own downsides vs test pollution.

The real solution would be to plan a serious refactor of how datapoints and theories work overall, to do things per-instance instead and make them non-static (there's been other issues looking for that too, like #127), thereby solving this for all datapoints, and ensuring everything is definitely nicely independent between tests. That's going to a bit tricky and quite a bit of work though, and has all sorts of backwards compatibility issues.