Sorry I haven't read this whole thread and maybe it's been mentioned, but watching racing this weekend they mentioned that Carlo Janka is skiing on the World Cup with no ACL.
There are a lot of advanced/expert skiers with no ACL. Before MRIs and ACL reconstruction surgery became established, some didn't even know they were missing an ACL for years. When EpicSki was active, I must have run across at least a dozen and skied with a few. They were mostly hard chargers who like steeps and chutes at places like JH and Snowbird. But there is no way to tell by watching someone ski, or even walk, and most ACL-deficient skiers don't talk about it. Probably because it really doesn't make much difference. Especially if a brace is not worn. Even with a knee brace visible, lots of people who have a brace are not ACL-deficient.
There are a few football and basketball players playing at a college or pro level without an ACL. Also rock climbers, tennis players, soccer players, and ultimate frisbee team members. I easily found examples when I researched the topic in 2012, the summer after I popped an ACL (not skiing). That was part of my decision process for not doing ACL reconstruction surgery.
This thread is mainly about my personal experience, with a few posts from other copers. For other topics related to ACL injuries, there are other threads.