Is this because of voters learning to strategize, or something else?
If it’s the former, then any amount of polling would do the same for them. We already know that Score and Approval turn into honest Condorcet methods under total strategy, and it isn’t hard to imagine voters being somewhat strategic and boosting candidates they prefer over the frontrunners in a bid to… well, beat those frontrunners. So the effect is pretty much guaranteed unless Score voters choose to stay honest for whatever reasons, meaning that there’s no real concern over this, since everyone will change their strategy before the election, or at least, after the first elections.
Edit: To correct myself, it’s actually the case that you have to give the maximal score/approve the Condorcet winner if you think they’re better than the expected value of the winner. As best as I can tell, this would likely mean the average of the Top 2’s utilities, which is a bit more complicated, and makes electing a Condorcet winner in Approval or Score less of a sureshot, and makes Score’s added expressivity valuable, though I see more room for a Condorcet winner in STAR, since its runoff is primed for one.
This is why Approval and STAR really take the cake over Score though, if you follow this one argument. Approval forces everyone’s votes to be equal, while STAR’s runoff makes it fairly difficult to be “strategic” in the face of new polling/voter strategy information.
Also, my counter to people supporting ranking is this: if 10% of the voters rank a candidate 1st place, and 80% rank that candidate 2nd place, the results will only report that candidate got 10% of the vote, crushing candidates who are good compromises/popular. Scoring and approving are the only way to show how much support each candidate got, independently, and STAR basically falls in this category, since all candidates other than the Top 2 are measured by their scored support only.