You and I may know this should never be committed. Hundreds of students and junior developers will read this post and
need to be warned that this is a VERY BAD IDEA.
I would rather make angry comments here than to have to explain why this is a terrible idea in a code review of an intern or a junior colleague.
Personally, I think the comments highlight why this can cause problems and what the alternatives are. Knowing the trade-offs and then choosing an approach is good design. Feel free to use that hack, but be sure you know what the trade-offs are, and what bugs can potentially arise in the future due to this hack.
I use this sort of trick all of the time when debugging, but I rarely commit any commented out code as a matter of principle.
Nobody was suggesting using this for "ghetto source control" or that this is an alternative to compiler directives.
Can't we just be polite and say "Cool hack, but obviously don't commit this type of code", instead of getting out the pitchforks?