The Doctor Who expanded universe in the 1990s regularly operated on the assumption that the Doctor's people (the Time Lords) actively stamped out alternative universes, being as they are the keepers of a one true timeline, which is why they sometimes employed the Doctor as a 'man on the ground' to ensure the correct outcomes are reached (eg. in Genesis of the Daleks).
Some of the more wildly inconsistent aspects of the Doctor Who universe as depicted in the newer version of the show from 2005-onwards have sometimes been attributed to the Time Lords being out of the equation. The entire continuity is in a constant state of flux, changing and warping from story to story and season to season, because the Time Lords are no longer there to ensure a single, unwavering timeline.
Some of the more wildly inconsistent aspects of the Doctor Who universe as depicted in the newer version of the show from 2005-onwards have sometimes been attributed to the Time Lords being out of the equation. The entire continuity is in a constant state of flux, changing and warping from story to story and season to season, because the Time Lords are no longer there to ensure a single, unwavering timeline.