I REALLY dont like idea of role-swapping officially swapping what you're ranking up for (new system)

Referring to one of the comments made in this video from a conversation the youtuber had with Riot: https://www.youtube.com/watch?v=TiS1FL2Klyc

Basically, players have been concerned that a high ranking (in one role) player would queue up for lower ranked off roles, then ask to swap to his main for an easy win to bring up his off-roles faster.

Riot's response was that there'd be no incentive to do this, because the system would detect that you've swapped roles and you'd rank up for the role you actually played, rather than the role that you queued for.

I REALLY don't like this. It feels like there are going to be so many issues because of this:

First, I'll give an example that literally just happened to me. I was in game 3 of my promo series to plat 4. Do or die. I got my main role (mid), and our support was quick to complain that he was autofilled. Then my main champion got banned. I offered to let him mid, and I went support.

What happens there in the new system? I automatically get to have that game NOT COUNT for my promo series, i.e. I get a second chance at playing my main champion for the series? I don't think that's very fair. The consequence to me only playing one champion in that role is that I can't dodge in promo series, if my main gets banned in promos I need to either play on another champion in that role or hope for a role-swap. In the new system, I could just convince someone to swap roles with me to avoid a really likely loss (and he HAS incentive to switch, because he'll lose ranking on an off-role instead of his main role, since once he looks me up and sees I have a 25% win rate on mids not named Ahri).

I feel like recognizing the opportunity to switch to support, and winning that game instead makes a lot more sense. I shouldn't get to just opt-out of my promo series.

Now, on to other potential problems:

• What happens with lane swapping? How can the game recognize if we've chosen to lane-swap at level 1, rather than role swap? If player A picks a legitimate mid laner and player B picks a legitimate top laner, and they both get hard-counter-picked, and they choose to swap lanes, I would argue A is still playing mid and B is still playing top. It doesn't matter where they go. The game is often decided in mid-late, where the initial lane assignments won't matter and the champions will play the same roles they do in those fights. These players didn't role swap, and it would be inappropriate to make the opposite rank be the one affected.

• Let's assume the system can detect this, it knows if I go Ahri top I should actually get credit for mid. Then another game I get top lane (or actually agree to swap to top), and some of my top lane picks get banned, and we already have a tank jungle and tank support, we have an AD mid, and the enemy team has a Kayle top? So I pick Ahri into Kayle and actually want to play her top lane (I'm not trying to argue here that this is the optimal choice, but given my comfort on various champions I think I would personally pick Ahri in this situation). Or for any player that plays off-meta stuff. Is the system going to assume they're playing another role, even if they go to that lane?

Just to me, when the answer is "don't worry, the system can detect this and we'll remove any incentive to abuse it" - I get really worried. One of two things will happen. Either people will figure out where the system is lenient and abuse it from there, or there will be false positives and people will get LP gains and losses not for the role they intended. There simply CAN'T be a perfect system.