I didn’t compare the gameplay of the two games, just the matchmaking and player numbers. You could easily use Overwatch or Call of Duty matchmaking as a comparison too. Online games with ranked multiplayer need a matchmaker that can balance the interests of its playerbase. AoE2 happens to have a small playerbase which means the matchmaker needs to be more restrictive if we want decent queue times and close ELO margins.
By definition, 1000 ELO is average. This is where I am in the ELO distribution, right on the peak:
