[rahoulb]

Yes.

As long as your code makes sure it takes account of that flag everywhere that it is used. Otherwise your new feature could "leak" into the system for everyone else.

Plus, as systems grow in complexity, there's always a danger that features step on each other. We'd like to think that everything we write is nicely isolated and separated from the rest of the system, but it never works that way - plus we're just a group of squishy humans who make mistakes. There will be times when having Features A and C switched on, with B switched off, produces some weird interactions that don't happen if A, B and C are switched on together.