It's a season-long event, you're not meant to progress fast by any means at all. I saw your argument about how only people who play tons can reach lv5 because of the time, and here's the thing: that's not a bad thing
If you're playing a lot and have been honorable almost every time, you deserve that level 5 much more than the dude he plays only a little with honnorable almost every time. You've provided more to making league a better community, and so the incredibly difficult to get award for honor should only go to the fewest and most noteable players in league.
Honor level 5 is not like champion masteries (up to 5), it's not something that just anyone can get. This is something not not many people are supposed to be able to get, so that it actually has meaning beyond "oh ya I'm a generally decent player".
For instance: when I see someone with lv.5 on a champion I don't go "wow he must be really good on that champion" I think "alright so he has some familiarity with that champion". That drop in meaningfulness isn't wanted with Honor lv.5