If I go "X"/SUP as role choices I still get Support almost every time if not always

As an ADC/ SUP main, this is quite a problem since I want to play my main (ADC) far more often than I want to play my secondary (Support), like any normal player does. But matchmaking always places me as support. This is the case for any player besides maybe JG who has support as their secondary main role. There is currently a system where if you filled or played support you get one of your 2 picks gaurenteed. But if one of them is Support (like your secondary), you seem to get only Support gaurenteed and NEVER your alternative. This is a bit unfair to us Support secondary mains since we don't want to play our secondary all the time, nor do we want to have to try and get use to another role choice so we don't just lose the game from unfamiliarity with the role's requirements/"fundamentals" if we don't get our primary.

So, how about this. If you just played 2 games (back to back) as the support role when it is marked as your secondary option, for your next game, your primary (non support) role is gaurenteed 100%. Then at least 1/3 games is on a role other than the way to common support role.