I'm didn't catch up on the thread, i just remember reading it initially because I felt a year without degredations seemed wrong.
So far though, haven't found any concrete proof from anyone that this is true. Riot previously has acutally said they really only look at last few months.
So, if you have some of these examples, where there can be some nice data collections we can look at for proof, it'd probably prove point better. For example, if can find low number cases for their 2 week ban, and then a hihg number case for their permaban, then we can tell that there was a significant amount of time between the two. (though tribunal may not have been around for that long).
But your making a statement without any evidence. If you can provide more data to look at, it'd be easier to have this conversation. (I agree with your premise, but I haven't seen proof its true)