The philosophy behind this behavior is the following:
If you used up all your excuses for one game, you violated the agreement on the game attendance given by the game conditions. You therefore already forfeit your right to participate with your first unexcused NMR. That is why your are put into Civil Disorder immediately and could already be replaced if you do not return fast enough.
The temporary ban is a separated measure build on top of it. On the hand, it should encourage reliable play by sanctioning the opposite. On the other hand, it should avoid that members continue to play more games than they can handle in apparently busy times and help them to get more reliable.
If you get temporary banned with an unexcused NMR in a given game, you already used up all excused NMRs in that game, but also had several unexcused NMRs before in that game or others. Therefore in theory, you not only disrupted the given game, but could not prove to get better too. The temporary ban comes thus in effect to sanction you, but also to avoid further disruptions in the game you attended.
Concerning the impact on the game, the temporary ban measure of course relies on the assumption that every open position will get filled up soon and further automatic NMRs are avoided. This appears to be working well so far.
Note, that in hardship cases you can contact us via the mod forum, so we could find a flexible solution.