I believe someone else already mentioned about why that in fact would not work well and I 100% agree that it would just make people stop playing ranked in general as it's part of the reason why i really don't play ranked.
Honestly thought it was obvious but that would be due to the added pressure from a win only rewards system.
Pvp games especially ones like apex already have a certain level of toxicity, even in pubs, it's not really avoidable, but the more pressure that's added to do well, the more it incorporates player toxicity.
In ranked game modes there is already an added pressure to do well because of the rewards gain and the potential to climb to higher level tiers.
With a win only rewards like they have done in arenas, it pretty much maxes out that pressure because now in order to get anywhere, your whole team has to play like gods.
There's no benefit for doing well yourself or carrying your team so a lot of people just look at their teammates, automatically decide they're no good, and just don't even try.
As a player who is around the lower end of being decent, I've been on both ends where I do very well in a match, get like 1k damage, 4 kills, 2 assist, and know the frustration for getting nothing for how well I did because we lost the match. The other team just being better or because my teammates couldn't hold their own. Losing out on something you tried your hardest to earn and not getting even a portion of what your could have earned, because lack of team strength makes people want to lash out.
I've also been on the end where I've played like absolute trash and do deserve 0 for how I played, but then my teammates are in the position above. They would have done very well and got nothing. And when people do well and still lose they start looking for the reasons why, and when they see the teammate with the lowest amount of damage, what do you think happens?
Let the cursing begin, because how dare you hold them back and for some reason they're entitled to voice their toxic opinion because you lost them the match.
A win only rewards system does very little to entice team work..sure it makes you want to get the win all the more, but it causes backlash when your team fails.
It doesn't mean you're going to communicate anything with your team or even try to work together, I've gone entire matches without a word or a ping from anyone until the match is over, and it's just them cursing for losing.
https://answers.ea.com/t5/General-Feedback/Ranked-arena-idea/m-p/11955289#M99629
I had my own idea for a ranked rp system, but it would only work for arenas. I know it's still flawed but the idea of it is to keep those players that belong in higher tiers, in those tiers, makes it a bit harder to climb so players who don't belong in those teirs don't reach them, and hopefully adds a little inconvenience to smurfs.