Challenges for Ranked Placement matches

I think there may be a better solution here:

There is still a considerable community of players that frankly, just don't play ranked. So when season 8 started and Riot released a challenge with an XP and BE reward for completing your placement matches, a large number of players who normally would not give ranked play the time of day "trolled" their 10 placement matches. Causing a much larger number of players to have their skill levels misrepresented and overcrowding the bronze division to resemble an apartment complex in Tokyo at double its max capacity. I'm hoping that as Riot makes these changes to the placement system, they go without creating an incentive to finish them. The abuse of that incentive in Season 8 created a huge problem in what even the devs call "a ladder with some rungs much further apart than others"

The solution I can think of is that instead of a reward for XP and BE, the reward becomes something that helps the player progress to the next rank. For example, a free win in their placement matches to rank up.

Much love, see you on the rift! ~KeenKraken