The mechanics of a steam engine are very different.

Reversing a steam engine with enough steam power to actually reverse "spin" the wheel motion of the drivers would indeed generate a lot of friction with the track (and probably quite a bit of track damage to the rail head), not as much as modern air brakes are designed to do against the wheels, because of the relatively small surface area of the wheels in contact with the rail.

By reversing and "spinning" the wheels in reverse you are putting a lot of "driver" surface area from the effect of that reverse spin against the rail, The drivers would get very hot (you're creating a lathe effect). So, with large spinning drivers, that would help generate a lot more heat, and if that could be done, would help convert momentum into heat eny.

This may be the source of where the current myth comes from.

This, as you note, was well before modern air brakes. And, as you've heard from modern diesel hogheads, you really can't do it, and have any of that effect with modern diesels.