"No, it's less effort than that"

He wants to present a low number, to encourage whoever he's dealing with on his end to do what he wants, gaining the benefit from that.

So he'll use every technique under the sun to encourage devs to give him a number he likes more, while never making it look like an order or coercion (which would make it his number - spoiling the whole play).

But when it inevitably takes much longer, he can point at the numbers the devs provided and say he was just communicating what they told him, so he's not responsible.

The only language these types understand is for requests for estimates to be "reviewed" to result in them always going up, to send a message.

For many reasons:

1) Estimations should be useful so business can adapt. In reality there's no adaptation of any sort, your PM will get the stick from its own boss that stuff needs to be ready by this or that more-or-less vague deadline. Thus, what am I estimating for if you don't care about my estimation anyway?

2) There are no incentives for teams ultimately to estimate anything realistically. What do you get for being accurate? A medal? In fact, all incentives go towards inflating the amount of work through estimates.

3) Ultimately all this dancing of estimates and rituals is nothing else but stuff that management embraces to appear more effectful and impactful than it really is.