>>43358345They tried.
Unfortunately, the Daleks have time travel as well. So... it kind of didn't work, and actually backfired when the Doctor's actions wound up convincing the Kaleds to go down the road to become the Daleks (Davros etc.).
The Time War, when it really got under way, actually wasn't really noticed by most of the lower multiverse, but it was devastating to higher life forms. The scale and concepts that the Time Lords (and then Daleks) exist in was beyond comparison. Entire civilisations, full-scale galaxy-spanning empires, gods themselves were obliterated as a side effect of some of the battles, mere collateral damage. Eventually, time was under so much strain that the Time Lords had to put a Lock on the war, which prevented anybody from shifting into or out of it using time travel, but not denying the ability of those in it to time travel themselves. Which, uh, fucked with things more.
The Time Lords could usually fix paradoxes (either that, or reapers appear and eat everything to fix it the old fashioned way), but the sheer scale of the shit that was happening over the course of the war eventually meant they decided "fuck it, we'll blow the whole universe from zero to infinity and ascend to godhood so we don't blow up with it" and embarked on their plan (they were going to be gods beyond gods). Bonus points, they thought it'd take the Daleks out in the process. (Ironically, it wouldn't have, because the Cult of Skaro was hiding out in their void ship.)
