You do know that the majority of League is balanced around Diamond tier and up with a bit of focus on the professional level because they have to be able to play without a LCS specific handicap. There has always been a constant requesting for more bans (usually 1 per player / 5 per side) so I assumed no one would complain with the 5 bans.
most champions don't have primary roles
EVERY CHAMPION HAS 1 MAIN ROLE. Yes they can be effective in another role, but every champion has 1 primary role even if it is only 0.1% more played than their other. And if it is such a hard concept to understand, then why not make it have a weekly, bi-weekly, or monthly update for the role which has been played the most over that past week, 2 weeks, or month. That role will become the current Primary and the second most played will become the current Secondary.
I looked through the list here, and could not find one where they had 2 roles of equal %. Sure there are a few close ones like
and
but they still have a Primary and a Secondary. This site takes the data from ranked games Platinum and higher and compiles it into percentages and statistics. This should be close enough to the skill tier the game is balanced around to be an acceptable projection of a champion's role preference.
If your concern is more for the word "Primary", would the phrase "current highest played role" work better?
That's only a phenomenon seen in competitive play.
A "phenomenon" is something (such as an interesting fact or event) that can be observed and studied and that typically is unusual or difficult to understand or explain fully. I am fairly sure we understand it and fully realize why it happens. You even said so in your second bullet point. If anything it is a pattern or a consistency, and could even be argued as being fully factual.