Forgotten Games Bureau: can't attach files or rate threads on that board
 

Self explanatory. It must be a mistake, Horseman can fix it in a minute ;)

I'm posting here publicly, in case more users had been frustrated when already found this, and they may have thought that it was intentional.

Fixed.

All the new boards we ever opened had this feature until someone request to have it fixed.

I think it might be the default setting.