Yes i've used Medite MRMDF for them with a painted finish and they've been fine. Wouldn't want MDF or MFC in prolonged contact with water but mine have worked well.
MR MDF is wonderful stuff. I've even used it with a T&G V groove effect for garage doors. I kept it well painted and after 20 years it still looked like new when we moved.
I think most of the plinths these days are just normal MDF with some kind of vinyl wrap around.
I'm sure you will be okay with MRMDF as long as you seal it and don't mop the floor too often, I would use 18mm.
You often see the MDF architrave and skirting they use these days looking a bit fluffy around the bottom in kitchens and bathrooms where it has soaked up water.
I've used MRMDF kick board in my kitchen and it works well provided you seal it well.
I sprayed mine with a pre-catalysed lacquer, colour matched to the cabinet colour, but if that is beyond your facilities you could try an edge sealer and apply self-adhesive aluminium foil (the stuff they use on insulation board joints) on the bottom and 25mm up the back. I find this stuff sticks like s**t and is totally waterproof.
Additionally to the above, for the edges I have used edge banding, and then sealed and painted the plinths. It's not expensive and gives a good professional finish. I also use the plastic sealing strip. Links below, but other makes/vendors available