This is an issue of pre-focus, not shutter release. Pre-focus manually by depressing the release half-way, or use the hyperfocal method if you can.
So you're at a birthday party. The main guest of the night walks in unannounced and you grab your camera and try and take a few shots of the excitement on everyones face as they walk in the door.
With a DSLR, especially a Canon that can be left on, but set to go to sleep in the on mode, I can grab the camera, point it at the door the person just walked in and fire off multiple shots within a few seconds of the person walking in the door.
With a P&S there is no way that would be possible even with the hyperfocal method. It's just not possible. Do they work for pre-thought-out shots when you dont want to carry a big DSLR, yes, but they dont work all that well unless the conditions are perfect.
If you have the time to sit and wait out the shot, line everything up and have a P&S or smaller camera produce a good photo, then you probably could have made the photo with a DSLR faster and come home with a better image
Just my .02 cents
There are hundreds of threads on here about reducing the gear we carry, but my camera equipment is one thing I dont skimp on