來源是最新一篇Riot dev的Blog文
https://na.leagueoflegends.com/en-us/news/dev/dev-updates-on-2020-ranked-matchmaking/
Promo Series:oward the goal ofmproving progression satisfaction and skill expression in our systems, it's looking likely that we’ll be removing inter-division promotions to reduce frustration of seemingly hitting a wall whenou knowou’ve been playing well. This means we'll also need to look at inter-division demotion protections to make sure that players are able to get where they should be in both directions without false limitations.
其中一段講明他們有意將晉級戰移除，以減少玩家「就算總體來說玩到很好，也有機會撞到鐵板」的挫敗感。
當然原文沒有一口咬定，但英文looking likely原本就有「除非出現重大變數，不然都會發生」的語感
刪除原因我也很有感呢...我朋友最近20場積分16勝4敗，其中三敗就是連勝上白金BO5然後0-3直接下去。