Exactly. An interview is work, on both sides of the table, and I see no point in distancing that work from what we actually expect the candidate to do once they get hired.

Puzzles, whiteboard coding, and so on don't tell me whether or not somebody can actually build software.

If the goal was to get free work, we wouldn't sacrifice staff time on the interviews. We'd give the applicant a challenging "homework" assignment and ask them to do it on their own time.