I'll bet part of why they're conflated is because every company that tries to hire 10X engineers, does it wrong and ends up hiring arrogant engineers.
Not to mention, to the much more numerous ranks of "1X" engineers, a 10X engineer, even a real one, is kind of a pain in the ass and hard to distinguish from an arrogant engineer.
Not to mention, to the much more numerous ranks of "1X" engineers, a 10X engineer, even a real one, is kind of a pain in the ass and hard to distinguish from an arrogant engineer.