Yes, but popularity doesn't make it right.
Look, there are lots of boards out there, and lot of mods. The ONE thing that sets the P4C series apart from similar boards from MSI, Epox, Abit, etc, is that it has the droop problem under relatively low load.
We're talking about ordinary overclocking, ie, bus speeds up to and including 250MHz. Any board designed for overclocking should support it. But the P4C series has trouble maintaining the constant voltage needed to get most Northwood cores that high.
You hear things about modding VDIMM and so forth on other boards, which are refering to extreme overclocks. That the P4C series requires extreme mods for ordinary overclocks is its downfall.
So how did the board get to be so popular? It got promoted by major sites. Asus likely sent the major sites "ringers", boards that were pre-tested to find which had the lowest occurance of voltage problems. Worse, many of the retail boards didn't show the problem until a few days to several weeks after the board was set up. It's a progressive problem, and reviews don't catch most of those.
Asus is a popular brand. The board performed well. A few could overclock great, especially for the few days a review site would use them. Some people bought the boards out of ignorance, others bought the board because it worked good at stock speed, both putting Asus's name as the major factor in their purchasing decision.