I fully agree that this is a sensible thing to do and have been doing it for years without any problems whatsoever but.......I found this in the Seloc Mariner Manual:
"For many years there has been the widespread belief that simply shutting off the fuel at the tank and running the powerhead until it stops is the proper procedure before storing the engine for any length of time. WRONG"
It then goes on to explain that fuel is trapped in the float chamber, passages and jets etc. It says the only guaranteed way to ensure all fuel is removed is by stripping down the carbs....
It also goes on to say that doing this removes the fuel/oil mixture from the cylinders, pistons and bearings (???? have I missed a meeting and have the laws of physics been changed without a vote?)
Now you can call me an old cynic but I suspect that while the theory they quote is right (ie fuel is still trapped within the carb in small amounts), it might have more to do with gasket kit sales than practicalities???
Like I say, I still remove the fuel line and let the engine run dry by itself and so far, after only 30 odd years of boating, haven't had a problem........yet!!