Lens and resolution on D3200 - limits???

I am not as smart as I pretend to be.  Not even close.

What does this mean?

"There is a downside to cramming so many pixels onto an APS-C / DX sensor, as Ken Rockwell explains: ‘… the D3200 has higher linear resolution than any other DSLR ever made in any format: 255 pixels per millimeter. (The 36 MP D800 only has 200 pixels per millimeter in its larger FX format.) Since the diffraction limit at 255 lpmm is f/6.3, any shots made at f/6.3 or smaller will have their resolution completely limited by lens diffraction, not the camera.’ You have been warned."

I think it means that if I shoot at f/8.0 the MP of the image will be less than the 25 max of the D3200?

Also I found this about lens and high meg cameras

"Images taken with the 18-200mm were sharp and contrasty on 6mp cameras, a little less so on 12mp cameras. Much less so on 24mp cameras. In some situations, the VR also helped keep acuity high. I was a little worried that a superzoom design would show some inability to keep up with 10 and 12mp cameras, but that's simply not the case--the lens performs okay, if not perfectly, on these cameras. Indeed, of all the so-called superzooms I've used and tested, this was the first one that I kept, at least until the 16mp DX DSLRs came along. I believe that the 18-105mm and 16-85mm both do better in the focal length ranges where they overlap the 18-200mm, so you don't buy the 18-200mm because it's thebestof the consumer zooms, but because it is good enough while extending the focal range. Also, the 18-105mm and 16-85mm are clearly better on high megapixel count cameras (16mp+)."

Can someone provide a general statement about lens and high meg cameras?

Thanks for any help.

d