6 years is long enough to know if there was some affect from this supposed backdooring of "billions of devices".
Why is it? Have you seen just how much mass surveillance the US government was undertaking in secret before the Snowden leaks? And there is no telling what other programs they are running, unbeknownst to the general population.
That's the nasty thing about surveillance: without whistleblowers / leaks, there is no way of knowing whether you're affected. Creating a false sense of security. Combine that with powerful 'nothing to hide propaganda'.. The rest is history.