If she doesn't know how to please herself, you are gonna have a hard time figuring it out. Plus if you get to 25 or however old and haven't, do you even have a sex drive? This is the worst marriage advice I've ever heard.
It assumes lack of consent towards your own actions, which is possible when forced, I guess. but then it is blaming the victim as it highlights the events as the victim's action, instead of the source of pressure fault.
Arguably, you could frame drunk masturbation as self-rape, as drunk you can't consent to your own masturbation??? Which wouldn't be victim blaming or it is???
Amen. Though I always heard it as, "Her fingers are for making things, not for diamond rings (nor for ringing the devil's doorbell)." Little pro-tip, fellas: if she's wearing a diamond ring, she's probably not the sort who's going to be rolling out fresh pasta dough, pizza dough, pie dough, bread dough, etc... for your dinner. There's a reason God put the rest of the woman around the sin cave.