I'm a little confused about their apparent implication that they have to single step all the way to the point that they want to inspect. Maybe older debuggers made you do this? But today, breakpoints are useful and seem to be widely supported, so you can run the program at full speed to the point of inspection, and then instead of getting a drive-by snap-shot as you do with a printout, you can do a more in-depth interrogation of the state of the system "Oh, this part of the state has value X as I expected, maybe it's this other part of the state instead--yes, there is something weird over here!" instead of discovering value X in the first run, adjusting your print statement, recompiling, and discovering the unexpected behavior.

All that having been said, surely there is still great value in applying a similar amount of consideration as to where to put the breakpoints as you would in determining where to put a print statement! (edit: and also in thinking hard about what new values to inspect if your initial guess is not borne out)