Pretty common nowadays. Long gone are the days when they would make the authors dress up for group covers. :P
We still don't know the gender of Haikyuu's author for certain (and they don't have a wikipedia page either).
But as usual, unless there's a lot of evidence to the contrary, always best to assume a shonen mangaka is a guy. And in the case of Gege and Furudate (Haikyuu), there are videos of them drawing where their hands/arms can be seen, and going off that, I think they're both guys.
Here's the video of Gege doing a quick drawing.
I'd say Gotouge for Kimetsu no Yaiba is most secretive out of all the Jump authors and for good reason. Couldn't even imagine with their success if people knew who they were.
It would be quite frightening.