Does WB not allow pictures before release date?

I tried to add some recently released behind the scenes pictures from Justice League One which is not in production but it seems you can't add them.

Is the case that the studio doesn't allow this?

Yes, this is why we can't add them yet

That's incredibly stupid of WB. Just like their movies.

Don't they want publicity for their movies?

It seems that the pages of WB movies are made available after the release of the film (maybe the day of release or the next one).

It's what happened for "Batman v Superman".