Yes and no. There has been a track record of journeyman types doing well at Melbourne, sure. But we have had a not dissimilar track record in that respect (I'm thinking guys like Shane Rodney, George Rose, Richie Fa'aoso, Brenton Lawrence. Could think of more).
Where we differ a bit is that Melbourne have often been able to cover the loss of their key players with a young, quality understudy. For a period there, they were signing up most of the Junior Kangaroos and any kid who looked the goods at a CHS carnival. Makes you wonder ...especially when there were always rumours around about things like, say, how well Israel Folau's family did out of him signing with Melb as a 15 yr old.
The lack of a salary cap below u/20s has allowed some clubs with strong financial backing to do very well out of junior development. By 20s, when they become subject to a cap, you've already had a few years to a) get a good idea of who's worth keeping and b) indoctrinate them into your system so there's at least a shred of loyalty there.