Riot stated before this last URF release that it was intended to be the final time URF would be available. They said that they were going to reaffirm their previous belief that URF causes burnout by watching the play counts.
Here's the problem with that. They released URF during a period of high-incentive/high-intensity activity in non-standard LoL content. There was a lengthy token grind event with high cost loot (and if you were grinding tokens, this meant you had already spent money, so *not* opting to farm tokens was unappealing). This was immediately after another token grind event (same thing - you had already spent money). These events were concurrent with limited time beta passes for Teamfight Tactics (no money required, but daily interaction heavily encouraged). Teamfight Tactics was also the optimal choice for farming event tokens due to the way surrendering works. Forcing a loss doesn't negatively impact other players' MMR, so there is no vote required to quit a game legitimately. Guaranteeing 4 tokens every 12 minutes or so (allowing for queue/load overhead beyond the 10 minute surrender timer) is a more consistent income than playing LoL in any mode.
I don't know about most of you, but my friends and I were already burning out from the events before URF's last release occurred. I still didn't play URF too much because of all the pre-existing event concerns. Do I think their prior in-house data shows a downward trend in active play after URF? Yes. It feels like they're trying to force it with this latest/last release, though.
_Note: multiple answers may be chosen (which is why I didn't use the native boards poll), but they're unweighted. This isn't meant to be a statistically rigorous demonstration, just a point of curiosity._