Had not heard that, but 5.2 adds buffering capacity to the mash to keep it in the 5.2-5.5 range.
But it doesn't add calcium and magnesium to your water if those are low, or adjust the chloride/sulfate ratio to better fit the style, etc. The various minerals needed to adjust your chemistry are much cheaper than 5.2, and with them you can address all these issues specifically for each batch/style. Yes, it's "one more thing" but it works and is not that hard with Palmers spreadsheet from his site.
If that doesn't hold interest, then 5.2 is great for mash pH adjustment.