Oh yeah I didn't say it was a great option but it's AN option and could be managed so long as your features are relatively self contained modules.

Major websites such as Airbnb have dozens to hundreds of feature flags which they use to run A/B experiments.

And so there is plenty of software available e.g. LaunchDarkly to help simplify the process.

there's a difference between temporary feature flags which eventually go away and permanent ones. say you build a new feature that has some overlap with an existing feature flagged one, and you unify some of the UI for it. now you have to always check what the UI looks like with one feature flag, with both, with none. as time goes on this gets worse, and maybe 3 or more features start overlapping in some way. If you're just using feature flags for A/B tests, this is manageable, but over time it can get really messy.