The project I work on at Microsoft uses feature flags. I see it with many Azure services as well. I can testify that it is absolutely if-statement hell, at least in the areas that rely on these feature flags. However, I will say I think 'lazy programming' is more the issue than the flags themselves. For example, isolating feature specific behavior to it's own impl and using an abstract class to share common behavior--that sort of basic stuff gets skipped in favor of 'time'.

Thankfully these are all obscured from the user for the most part.

We have a 'control panel' like thing that we used to enable/disable feature switches. It works well for its use case and let's us enable/disable with as much granularity as we want.