Quote from talontrading:
if you do not realize that these two positions are synthetically equivalent, you're missing an important piece of how options traders think. There is a world of difference between how experienced options traders and retail guys think. There is a reason that floor traders can go home with hundreds of millions of dollars hedged with synthetics and sleep pretty well. (It's also interesting to know where those hedges can break down... things like boxes are not perfectly 0 P&L.... but based on your post I don't think you were driving into subtleties like that.)
Consider this case... what if you had a buy write in MON today, 47.50 strike. Stock closed today 56ish and the call was 8.50 @ 8.75 on close. Now, how do you unwind that trade if, for whatever reason, you wanted to be flat? Paying the spread on the call is unattractive, but simply buying the put which was 0.17 @ 0.18 = basically no spread.
Bottom line is that a covered call is kind of a silly strategy and rarely appropriate. Understanding that it IS a short put highlights that for a lot of "investors". Unless you are doing HUGE size, the two positions are exactly equivalent.