You know, I find that people of the past generations were in a real hurry to potty train. I think it goes back to the days before quality disposables & cloth diapers, and back before nice modern washing machines. Potty training was more about mom's convenience and getting out of a dreaded chore. And of course moms played the comparison game.
If something seems wrong to you about this potty training system, trust your mommy instincts. And try in a diplomatic way to make more of a boundary with extended family when it comes to your parenting decisions. I highly suggest that you read the bean dip thread in Gentle Parenting for a great way to do this!
A personal story along these lines... my oldest dd was about 4 at the time, and was peeing in the potty like a charm.
But for #2, she still wanted her trusty diaper.
I was ok with that. I went out of town for a couple days due to a family emergency, and my MIL came to help out my husband.
When I returned she told me that she had wanted to go out and get some supositories, and that using them and making dd sit on the potty would work like a charm. She had meant to do it while I was gone, as a "surprise" to me when I got home. I was in shock!
I was so glad that she did not go through with her plan!
I could hardly imagine something less respectful to a child... oh I get mad just thinking about it!