Perfectly agree with this. Making a sub use a dildo or a strap on could be the domme saying 'sorry, your pathetic bits are not good enough for me. To get an orgasm I need a big dildo inside me. However, if you are a good boy, I will let you wear that dildo so you are at least involved'. Its a form of degredation and humiliation. There are also humiliating gags which have dildos as part of them that the sub wears while the Mistress straddles his face. Can also be combined with queening/suffocation.
I think any form of stimulation can be a reward or even a punishment. A domme can give a male sub oral sex (very nice) but then stop if he has not performed to his best in some task or other before the climax. Spoiled orgasm is a common technique in femdom.
Also, if you have a male sub bound and helpless, you can tease him any way you like for as long as you like and make him beg for release... of course if the sub is gagged you may not hear him beg so clearly...![]()