I also don't think many reports actually assert that CA was responsible for, say, a 10% swing. Why people are taking this serious is, I believe, because we now know that it's possible to get such data and we have seen the sort of feats that machine learning can do today. It's doubtful that CA was the company to successfully combine those two ingredients. But without changes it's all but guaranteed that someone will soon will.
Plus there is the fact that the election just happened to be incredibly close. You can make a list with about ten possible reasons for the result, from people being tired of Hillary, to the FBI's strange moves regarding the e-mail investigation, third-party candidates, russian trolls, the free media Trump got, Cambridge Analytica, and probably the weather in eastern Ohio. It's possible that the absence of any two or three of these would have changed the outcome.
[0]: example: https://www.vox.com/science-and-health/2018/3/23/17152564/ca...