I doubt they have forgotten. A lot of people will make sure to remind them of their bonuses. So it might be bad budgeting from the side of the companies. And even if you do get these bonuses, a lot of the ones that look too good to be true are actually bonuses with hooks attached. So for example, you get a large bonus for something, next step is you need to play some game or do some thing before you are allowed to withdraw it. Ive seen it before, but only in shady gambling websites.

Most of the time gambling sites know how to inform and plan.