If Thanos had, instead of randomly wiping out 50% of all living things, he had instead in each species wiped out only the dumbest 50% what would the reaction of each avenger have been?
It requires a single doubling to get back to where we were. To double, you'd need about 10 times a 7% growth. Probably within less than 100 years you'd be back at the same problem
Not to mention that when you murder a shit tonne of people, and when it's over you'll likely have lots of people getting babies, so you get a birth wave about 9 months later. That regrowth starts FAST.