People here are conflating a decimal calendar or decimal time with metric time.
In its evolved form as SI, the metric system very much does have a unit of time. It is the second, and one can apply metric prefixes to it. So to those wondering what it would look like: It would look like, and does look like, kilosecond, megasecond, gigasecond, and so forth. I'm sure if you think about it you will recall having come across milliseconds, microseconds, or nanoseconds, somewhere in your lifetimes. (-:
In its evolved form as SI, the metric system very much does have a unit of time. It is the second, and one can apply metric prefixes to it. So to those wondering what it would look like: It would look like, and does look like, kilosecond, megasecond, gigasecond, and so forth. I'm sure if you think about it you will recall having come across milliseconds, microseconds, or nanoseconds, somewhere in your lifetimes. (-: