I would swap the main purpose and the "big advantage" below. (I would also not use "big advantage", that's too subjective)
The main feature of the class is to be bound to the global clock managed by the component, the strictness (and consist behavior across versions of PHP) is bonus.
We might also tell that all clock implementations in the component return a DatePoint?

thanks, here are some proposals

LGTM once my two remaining comments are handled, thanks!