So you can't accept that time travel can lead to alternate timelines? That's the usual view of people who assume time is strictly linear and completely unmutable. Maybe that's the case in reality, but in Trek we've seen that time can be altered, and that there are many different ways to travel through time - slingshot effects, wormholes, orbs, time travel pods, even temporal transporters.
You're assuming that the only time travel that can occur is if it is a predestination paradox, which isn't the case. Calling other instances of time travel that don't result in predestination paradoxes "plot holes" is incorrect.