My players can roll in the Game Log, but the DM cannot. Why is that?

This seems awfully odd for a game whose most basic premise is that the DM rolls dice to determine what happens.

I could roll a physical die, but often I want to roll "in front of the screen".

I understand that some DMs make a fake PC for this, but this just seems silly.

What are other DMs using? Is there a mechanism I'm missing on D&DB?

We play PBP and do not use a VTT (as Maps won't work asynchronously.) 

You can roll dice from 1 of 2 places with Maps; monster stat blocks and the game log itself

For monster stat blocks, you click on a monster token, click view stat block (right of its hit points) and then click any of the buttons in the stat block that opens in the sidebar.

To roll from the game log, click "Game Log & Dice" in the bottom right of the screen (the club icon) and then expand the Roll Dice menu at the bottom.

You can also roll from the encounter builder when you run an encounter.

Though by default, the DM's rolls are not shared with the players.

Thanks, Davyd. Interesting!

So I can roll in the Game Log, but only from Maps. Hmmm.

We can't use Maps for the maps - we're asynchronous, so Maps times out before the players can see it. But they are used to rolling in the Game Log from their character sheets.

So maybe I could launch Maps with no maps, just when I need to make a public roll, which will then show up in the Game Log where players can see it. Not ideal, but it works!

Hmmm. I'll need to play around with Encounter Builder again. I've never loved it, but I'll give it another look. Thanks for the tip, @jl8e !

Any rolls rolled from maps will be shared in the game log.