The issue of the lense is very relevant if the individual is going into Professional level photography. A digital camera will produce a 'quality' of image popularly touted as mega-pixels, which whilst rooted in reality, is more a marketers device than anything else. With a digital camera there is a limitation on how far you can zoom into the picture taken before it gets blocky. The greater the concentration of pixels in a given area the more you can zoom in, but its still finite.
This paragraph doesn't actually make sense. What does "zooming" in have to do with megapixels? The light that the CCD receives is no different than what film would receive. Up until that point, it doesn't matter if you are using a film or digital camera. The lens is delivering the same image. Film is finite, also. Depending on the speed of the film, it could have severe limitations, too. An ISO of 800 is going to have a large silver halide in its emulsion vs an ISO of 100 which is a very small grain, so you have a lot of the same limitations as you would a 3 megapixel camera versus a 10 megapixel camera. The lens has nothing to do with it, though.
Just like different film speeds, you can get grainy pictures if you use a low megapixel camera. But, you really aren't going to see degradation in picture quality on even a 6 megapixel camera unless you are enlarging and printing to an 8x10 or larger (and, even then, if it is something you are putting on your wall, you still won't see it).
As a rule of thumb, if you plan to hang a picture or put it in an album, you need 200dpi per printed inch. That means that an 8x10 ([8" x 200 DPI] x [10 x 200DPI] or 1,600 x 2,000 pixels, or 3,200,000 pixels) would need a 3.2 megapixel camera or better. So, a 6 megapixel will get you almost 300dpi per printed inch, which is pretty much standard for prints (unless they are using a negative free print process, which prints on traditional media).
