I haven't used machines in long enough now that I barely remember what it was like building strength with them, but I'll never go back. I can say in my experience compound lifts with a heavy load that must be controlled in all planes are superior to the typical exercise machine. But then again, that's just my experience and what I know works for me based on my own training. I don't have any empirical data to back it up (although I'm sure there's plenty out there making this argument) and freely admit that what works for me may not work for someone else.
In the end I'll oly lift for certain benefits just because I enjoy the oly lifts too much to look for another way to do it. There's something so wonderfully violent, aggressive, and savage about them. I do agree that there's nothing "magic" about the oly lifts other than the fact that they are yet another compound movement that trains multiple groups and builds strength. Lots of ways to skin that cat and as always the most important thing is to actually do the work.