Hi, Since mounting plates are necessary for these hinges, could you please explain why they are sold separately?

With our concealed hinges, the mounting plates are sold separately due to there being different size requirements of the mounting plates to suit the application. Also, they may also be required separately, in situations where some are missing or needed for replacements. This is something as a company that we are trying to improve on and feedback regarding this particular product has been passed onto our website/product team.