I have had two accounts and am nearly max th8 and th9 at this stage, at the lower levels your focus is on loot not on trophy climbing, but for those who do trophy climb at lower levels the reaper would be available. If your leaving your town hall outside and just trying to get loot to upgrade as much stuff as you can the reaper would end up being dead content at lower levels. It would be available at TH6 but only once you hit gold league.
As for the DE cost 150 for 3 active reapers, the cost of an army is usually between 75k-150k at low levels so even if you win 1/3 defences at 100k for the army your getting 20k elixir (not to mention a % of DE if they use dark troops) for doing pretty bad in defense if you did well you would be getting 60k+
