Thanos had a horrible policy. In many cases it wouldn't help (either it would cause societal collapse or things would go back to being a problem), and even when it does it would usually not be worth it.

If he has to get rid of 50% of the people, shouldn't he at least put them into some sort of computer system, so the remaining people could at least talk to them after?

Then put a guardian system in orbit around every planet to protect the uploads and prevent any recurrences of problems.