I highly suspect this is outdated advice. Technically there was some ambiguity about whether 12pm/am would denote midnight or noon, since am/pm are relative to noon. However, the computer age has utterly removed that ambiguity. 12pm is noon, 12am is midnight. Digital clocks have spread familiarity with that convention widely throughout the developed and developing world. I doubt there is any serious confusion any longer.

I suspect that this is a piece of advice (avoiding the use of "12pm") which particular crufty old newspaper editors hold onto dearly even though it has passed out of utility.

I regularly see people getting 12am and 12pm mixed up -- using midnight and noon definitely reduces confusion.

You'll still confuse people (generally outside Anglo-American culture) who are used to 24-hour digital clocks.

If they've not familiar with pm timing, they'll be confused for the entire afternoon, not just noon.

They'll almost certainly have encountered am/pm times before, but nobody teaches you the 12pm = noon convention.

Yes, I distinctly remember learning as a child in the 1980s that 12pm was noon and 12am was midnight. I also remember being confused because I thought it should be the other way around at the time.