Steelmanning: Discover the truth by helping your opponent
The problem is that steelmanning is only useful in one kind of argument (the kind in which each party would rather discover the correct answer than "win"), which is increasingly rare compared to the other kind (in which each party already <i>knows</i> their opponent to be evil, deluded, or both).  Debates that include an audience are almost without exception the latter sort, in which steelmanning is worse than useless.