It is a viable tactic.
In large XC fields there will almost always be a runner or several who know that their best chance is force an honest pace early on. Because XC is (especially in courses that are not firm underfoot) more tiring it's risky to let people get away too far, it's also harder to gauge the distance, depending on the course.
There are also people with a pretty bad kick who will most likely lose if they wait too long. And might lose more than one position if they do not run the wheels off some competitors. It's more rarely possible in track races unless one is far superior. But putting some distance between the front runner and the field is IMO better than working as a free pacer for the rest. It's also more difficult, especially in deep fields, that's why it's more frequent in college women than in professional men.