I guess, but the biscuit is designed to swell by absorbing the water based glue (that's why they don't work well with urethane glues) so I wonder if 'contact' is an really an issue. I've seen them used on MDF where they swelled enough to ghost thru to the surface. Don't get me wrong, I'm not a fan of biscuits except for butt joints when the extra work of a mortise and tenon doesn't seem justified (mother-in-law projects). And because the slot is slightly larger than the biscuit to allow for expansion, in my experience they're not that good for allignment. I'm back to the way I was taught 100 years ago using cauls.
I agree, that same 100 years ago, our first project was to hand edge joint two boards and glue them with white, not yellow glue. The next session the shop teacher would break them over his knee to demonstrate that if they were properly jointed, the glue joint was stronger than the surrounding wood. If they broke on the glue joint it was, start again.