I used to think that too, but is it really? If estimates are always wrong, then is there really much of a difference? Besides, the lead often has business related information that informs his decision of "this feature must take no longer than X amount of time or we're going to have problems with Y" where Y is often political and not technical.

It just goes against agile development so it seems like if we're doing that, we're not doing agile. Then again, nobody is it seems? :)

I remember when Agile development used to involve chickens and pigs. If you have no idea what I'm talking about, then you're not doing Agile as it was written. Almost nobody is today.