Why Does a DSLR Need a Shutter?

This has been at the back of my mind for awhile now and Underoos post about sensor cleaning brought it to the forefront.

In a film camera a shutter was necessary to control the length of time the film was exposed to light.

But, why does this matter with a digital sensor? Why not just energize the sensor for the right amount of time to get the proper exposure without having a mechanical apparatus that flips open and closed? Isn't that how cell phone and p&s cameras work?

Is there something I'm missing here?

google is your friend.

Well, you just took all the fun out of that.

Quote:

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Originally Posted by Chainsaw_Willie

Well, you just took all the fun out of that.

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You said the same thing to me once, and I think I replied with "so is Chainsaw Willie"