Do 'Deadpool 2' Post-Credit Scenes Matter?

Deadpool 2, the latest X-Men movie from 20th Century Fox, introduced the mutant Cable, who is a time traveler. Time travel is something that the film's writers played with during the film's post-credits scenes, reversing the fate of one character and potentially bringing the events of the entire film into question.
The entire plot of Deadpool 2 involves Wade Wilson searching for a purpose after his love, Vanessa, is killed.