Cee
i don't remember a reason, just a complaint.
the problem is players getting promoted with levels to low to compete. this has nothing to do with inactive players.
You're wrong, inactive players is the main reason why players get promoted too quickly and end up in Elite at very low levels.
For the majority of leagues, Rookie is filled with mainly inactive accounts so anyone who bothers to set up and set a strategy is likely to promote in their first or second season.
Pro is usually filled with inactive bots (to trigger promotion) so again, anyone who is active will most likely promote and find themselves totally out of their depth in Elite only three or four seasons after starting to play.
Adding an extra tier would simply add one or possibly two seasons to a newbies progress to Elite and they would still be too low a level to be competitive.
The answer is not more tiers, it is more players, fewer leagues or a total overhaul of the current tier system. Probably a bit of all three.