I think dielectric grease is better than no protection, especially around the outside of things. And the physical contact made between connector components will push the grease away as they slide together. So it will work internally as well. But the studies I read showed how the conductive grease improved the current flow over dielectric grease. Which seems a definite advantage to me.
Interestingly "dielectric grease" is actually simple silicone grease. The same stuff used for O-rings, seals, high temp applications, brake pad mounting, and so much more. But you can buy a very large tube of silicone grease for a fraction of the cost of a tiny tube of dielectric grease....marketing. However even more interesting, the conductive grease I talked about is also silicone grease but with a ton of carbon dust added. And it is even more expensive than dielectric grease. I don't know how much carbon costs, but it seems like someone is making a lot of money on all of these products.
I should also note that carbon/graphite mixed with silicone grease creates a very messy product. The black color of the carbon gets on everything it touches. And the silicone makes it a little hard to clean off. Need to use some caution to prevent a unwanted stain on something.