The core theory of Netflix's wild run to a $175 billion valuation hasn't been debunked with one quarter of slower growth than forecast.

But the Q2 miss might make some investors reconsider why they're betting on Netflix in the first place.

The basic hypothesis for bulls is that Netflix is on its way massive global subscriber growth that will eat away at legacy media companies. As I wrote about here, analysts nearly universally expect Netflix subscribers to keep soaring -- to 200 million and higher by 2020.

Nothing announced today undercuts that general idea. Netflix again announced significant growth, adding 5.2 million customers to 130 million global subscribers.

The problem was the company's own internal prediction pegged that quarterly number at 6.2 million. Missing by 1 million customers is a lot, especially because Netflix has gained a reputation for beating its own estimates. Netflix also didn't really offer a reason, other than blaming their own forecasting models. That's why the stock is down about 14 percent in after-hours trading. Netflix, itself, called the quarterly results "not stellar" in its letter to shareholders.