Soaking the frog yourself is not actually necessary. Although it is beneficial to soak them once a week to help remove old sheds that didn't quite come off all the way and also allows you to interact with your frog somewhat. While frequent handling is frowned upon and causes stress as Pacman Frogs aren't to keen on being handled. It is still beneficial. It also allows them to exchange stored water within their body. Some will use their given water source on their own frequently while others hardly at all so if you soak your frog once a week or so it will help the with hydration and removing old sheds, but also allows them to get used to you so they are not scared everytime you're around or have to handle the frog to clean the enclosure.
I hope this helps answer your question.