I lived in Houston till I was 21, and this storm is unlike anything I could have wrapped my mind around. It's just so much water for so many days, I feel like I'm almost numb to it because it's just so insane and terrifying. However, I do believe that the decision to not evacuate the city was completely justifiable. When people evacuated during Rita, it was pretty much a shit show, and more people died on the road than from the storm.
Hurricane Harvey: Why Didn't Officials Order Houston Evacuation? : The Two-Way : NPR
"In searing 100-degree heat, cars crept up north I-45, windows down, air conditioning off to save precious gasoline. The traffic jam stretched for over 100 miles and has been going on for over a day and a half. ... Gasoline was not to be found along the interstate and cars that ran dry made the gridlock even worse. Abandoned vehicles littered the shoulder lanes."
Plus, the conventional wisdom has always been that if you can, bunker in place and wait out the storm (usually in an interior room without windows, like a closet). It will take years to evaluate how Houston handled Harvey, though, and this storm will be useful in policy planning for the next one.