Dispute about number of large water bodies

Henry Kissinger is quoted as saying:

I formulated the rule that the intensity of academic politics and the bitterness of it is in inverse proportion to the importance of the subject they’re discussing.

This is known as Sayre’s Law.

Which brings me to Feng et al., a study published recently in PNAS:

The abundance and area of WBs [water bodies] over large regions are critical information for water-resource management but remain highly elusive. For example, the number of lakes larger than 0.1 km2 at the global scale was estimated to range from 246,146 to 4,123,551, more than 1 order of magnitude difference among them.

I’m not sure I accept the premise that such estimates are “critical” for water resources management, but anyway…

Using satellite data they found that:

WB abundance in China exceeds all previous estimates. The abundance of WBs (>1 km2) is estimated to be 6,821 in our study, 1.3 times the previous highest estimate (5,535) and 2.5 times the lowest estimate (2,693).

This was met by a challenge from Zhang et al.:

When compiling a lake inventory, reservoirs and dams should be excluded, and a relatively stable season for WBs should be chosen to avoid seasonal, interannual, or longer variability… These considerations are not addressed by Feng et al., leading to the feasibility that the maximum WBs number and area were estimated.

Feng et al. replied this week here (if you care).

I don’t question the scientific validity or merit of addressing these questions, but someone needs to explain to me why this inconsequential stuff warrants discussion in a high impact journal like PNAS.