Oil & water doesn't mix...baby oil, as we are specifically discussing here, creates a barrier that will not let your skin pull moisture back in to rehydrate.
A customer of ours discussed this issue today. She has been tanning off & on for many years and was considering giving it up because her skin was getting dryer. She blamed it on tanning (does use tanning lotion). When she explained that she uses baby oil faithfully as a
moisturizer after her shower I told her to put it away forever and explained why. She caught on immediately and couldn't believe what she's been doing to herself all of these years. The oil may feel nice on top of the skin, but does not add moisture as she so desperately needs right now. I told her an order of Glimra's Max Hydration would be arriving in the next day or two, and she'll be back to buy it.