For the web, probably not. but when you go to print, the pixels come in handy.
You mean to tell me that when i resize a 24 megapixel picture, it will be compressed into even higher pixel count when its made smaller?
Um, no. Each display device (monitor, projector, printer) has its native resolution. A computer monitor may have resolutions in the 72-96 pixels/inch range. An inkjet printer has usually at least 300 pixels per inch, up to over 600 pixels per inch resolution. Let us assume you have an image that is 6000x4000 pixels. At the 96 pixels/inch, and assuming you are showing the image at 100%, you'll need a monitor 62.5 inches wide by 41.6 inches high. On real monitors, you'll only see a small portion of the image at 100%, so you need to downsize the image to fit into the actual monitor space.
If you take the same image and print it on a 300 pixels/inch printer, at 100% resolution, that would give you a print of 20 inches wide by 13.3 inches high. A printer capable of 600 pixels/inch will give you a print size of 10 inches wide by 6.7 inches high.
By cropping in post, you are reducing the number of pixels that your image contains. This won't matter much when displayed on a monitor, but will when you want to print full-size.