I would like to quote your own words, keep in mind you've told others the same: Note the exception when it comes to premades. Outside of that exception, we see zero fully solo queue matches with Master+ players that have anything but Master+ in them in our data since the change.
This heavily implies a huge contradiction, either you're looking at gold+ pre-made only or master+ pre-made only. Even so you're still ignoring other programs facing rank this season.
This change overall impacts well over 90% of the players.
I would like it if you could provide the data for this claim. As a Riot official a claiming like this, especially when contradicting yourself and other players experience, it would be of significant help to see that data and figure out why it feels and seems the opposite. Sorry if this comes out offensive or anything like that as that's not my intention, just there's too many contradictions.