It's something we have been thinking about a lot. As you write, there is no real good way of dealing with this. Stating both options will make theses read convoluted.
Writing the thesis as a question doesn't help much either and confuses some people. (We have tried.)
We think that the best place to correct for anchoring and setting up the stage for a discussion is the discussion info, the popup that appears the first time you load a discussion.
Regarding the "should abandon" and "should embrace", what kind of new claims do you think would arise, compared to a single thesis "should abandon"? We normally were able to fit all claims of two theses multis in comparative single thesis debates, sometimes though not at the first level as they require an implicit assumption to be stated as a parent pro or con.
We leave it to users, but consider comparative single thesis debates much easier to write than multis with a lot of linking. If there are more than two options though, multis are required.
We see most multis in team situations, not public discussions, e.g. us discussing which framework, library or design to choose.