The first step would be to understand anatomy. For some women (perhaps many or even most), a vibrator "shoved into their pussy" isn't going to cause an orgasm. You'd want to direct that vibration toward the clitoris. Scientifically speaking...
"women over 40 years of age were more likely to have experienced orgasm by stimulation of more than one region of the body, whereas women between the ages of 18 and 29 were more likely to have experienced orgasm by clitoral stimulation alone."
Source:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5084726/
Also: "General statistics indicate that 70–80% of women require direct clitoral stimulation to achieve orgasm."
Source:
https://en.wikipedia.org/wiki/Forced_orgasm#cite_note-Rosenthal-3
Secondly, forced orgasms for some is like a form a torture. I get VERY sensitive after an orgasm and continuing to keep going right away is awful. Sometimes I will eventually move past that and orgasm again, but a breather in between is well appreciated. It is more like...sensory overload. My owner is really into forced orgasm play, but to me, it's almost more of a punishment. Of course, I like parts of it, but it's not an entirely enjoyable experience for me.
As for if it can be painful, my owner has never pushed it very far in that direction. He is slowly working me up to being able to do more. But yes, it can be painful.
"The point of (consensual) forced orgasms is pleasure. But forced orgasms may not be pleasurable the e-n-t-i-r-e time. "Typically, forced orgasms start off as being pleasurable,” explains Carly S. “But [as] more orgasms occur, the body can become so sensitive that the orgasms become overstimulating and even painful.” However, orgasms release a whoosh of feel-good endorphins."
Source:
https://www.healthline.com/health/healthy-sex/forced-orgasm#how-it-feels