In times past, the mechanical "timers" were clockwork affairs on most 35mm SLR cameras, they were rarely used by most people. Many of the cameras I would see come into the shops for repair were either impact damaged or the shutter was "hung" after a timer had stalled mid-release. With the advent of digital photo that condition has been erased. And accuracy/consistency improved. More points for digital!

Digital counters are great and available in most digital cameras. There are a couple of "timer" functions on my Canon cameras. First, of course, there is a count-down timer that can be set for 2 secs or 10 secs. The 2 sec counter I use if I have the camera of a trip-pod and just want to take a pic and reduce possibility of camera shake from pushing the button, usually when I'm using a very slow shutter speed. The 10-sec counter is useful when I'm taking a group picture and want to have time to get in the picture. Then there is "bulb" mode where you can set the exact time the shutter will be open - 30 secs, 30 minutes, what ever you want. I've never used that yet.
Then there is a built in intervalometer that all take a pictures every X seconds for Y person of time, and you can set both X and Y. This is for time-laps movies.