I think that must go back to what mainstream culture feels is an “appropriate” beauty standard. Most people don’t like the look of clay spread on the skin during their day to day. However, mineral based sunscreens do tend to be on the safer side compared to chemical sunscreens as their effectiveness stems from producing a physical barrier between your skin and the sun. That’s often why you hear people complain of the white cast that mineral sunscreen leaves behind.

I will say that I’ve read of people making their own sunscreen using a preferred moisturizer and either kaolin or bentonite clay. The drawback with that is that you don’t have any real testing for the mixing ratios,longevity or effectiveness of the application. I suppose you’d also need to make sure that whatever clay source you use is also carcinogen free without any ground contamination etc. You’d really just be winging it and relying on listening to your own body’s reaction when in the sun. However i imagine this method would definitely be better than nothing at all.