Partly this, partly because it was treated as a ELO reset and everyone starts at the same ELO score after each LEC restart. You have a giant pool of players all starting out near the same ELO level so matchmaking can easily find a similar ELO rated player and at the same time, someone who is close in latency.
I know the next question will be, "when will the Season reset happen for Online Ranked and UUT ranked!" I hope for it to be soon, but cannot confirm when. We are making some improvements to ranked modes and I want to get everything in before we do a season reset, so it feels new and exciting for you guys.