It got autopopulated in my IDE, and *sounds like* the function I intend to use. Possibly even one I've used before and am mis-remembering the name of.
The "Here be Dragons" got added later, when the signature of the function didn't change (or it did, but duck-typing, so no-errors, let's go!)
I was told about the function verbally, so I never read the docs. I then told someone else. At some point, the oral tradition drops the "Here be Dragons".
In a less formal code review (maybe someone in charge of many programmers, who cannot do a full read of all of their code) there is no way to easily have them find it all using grep.
If any of that happens, you absolutely positively deserve everything you get. DO NOT call a function if you don't know what it is!
My actual assertion, BTW is that duck typing has advantages to go with the disavantages.
I have worked on a number of large projects with multiple coders. I presume you use the old cut'n'past code 'sharing' method with a significant appearance of the cargo cult antipattern?
Your solution is really fragile. It requires never changing classes once they are created (at least the public members thereof) because you never know if they are used. Which, in some languages, or with some programmers, is all the members.
You need to RTFC as well. Surely you don't recommend unilaterally changing code used in other projects!