Yes, I agree. DPI is incorrect terminology when resizing an image in Photoshop -- PPI is correct. However, what I'm referring to is the pixel pitch (also known as dot pitch) of monitors. Back in the day, a pixel pitch of .3mm to .4mm was the norm. Today, monitors can have a much tighter pixel pitch. This resolution directly affects the image size. An image spec'd at 75 ppi will appear much smaller on a 1920×1200 monitor with a .27 ppi pitch, which corresponds to a native resolution of 94 ppi (if an image is to be best viewed that type of monitor, it should be spec'd at 94 ppi).
You said "The image dimension (in pixels) must be compatible to screen resolution". I'm saying there is no definitive global screen resolution, so an estimation must be made about the dot pitch of monitors your images will be viewed on.
The dot pitch value fix the size of a rendered pixel. I agree.
But this value is related to DPI value, not PPI value.
You cannot modify it changing the PPI value embedded in the image file.
If you are in doubt do the following simple test:
fix the PPI value to 1 and save the image =>IMG1
fix the PPI value to 1000 and save the image => IMG2
Do not resample, otherwise you are changing the image width and height.
The pixel-width(height) of IMG1 are equal to the pixel-width(height) of IMG2.
Now open IMG1 and IMG2 and check for difference.
For web publishing, it's more simple to think about screen resolution.
If you want to get audience from about all the surfers, you must remember that 800x600 is the resolution of the old 15' CRT.