Board Thread:The Flash discussions/@comment-5137743-20161022202353/@comment-3221148-20161022205926

Speedsters' time travel apparently affects the timeline in a much more profound way than time ships'. Speedsters basically rewrite timeline, allowing them to either coexist with their other time's selves (when Barry went to Wellsobard time period and met Other Barry), OR superside them (like what happened to Barry's time travel back in Season 1 of Flash, Season 4 of Arrow, during and after the Flashpoint). It's likely that supersiding effect that greatly affects timelines, leading to events like Flashpoint, or Eobard's loss of Speed Force after he killed Barry's mother (it made Barry's future as the Flash uncertain, requiring Eobard to make sure the Flash is created for the Reverse-Flash to exist, resulting in the timeline seen in the shows).