If one has 500 PAs and strikes out 10%, that reduces chances for a successful at bat by 50.
If one has 500 PAs and strikes out 40%, that reduces the chances for a successful at bat by 200.
Strikeouts don’t operate in a vacuum. If the K rate is high enough, chances for successful PAs also are reduced. Hence an impact on OPS and other performance numbers.
If a high K hitter doesn’t walk, that makes things even harder. Walks (theoretically) provide “free” on base success. If a high K hitter doesn’t get those free bases, he has two obstacles to overcome.