It's not gonna be A+B+C... More like A+B... but if G happens, then L,M,N,O,P. It's an irregular continuum; You won't get it all in a 10 minute YouTube video; but there's some good stuff out there... if you can weed it out from the BS.
Yes, in a perfect world, grass and water are all they need. But most of us don't do it in a perfect world. Management-intensive grazing can help to optimize nutrition during the grazing season, by managing grasses, forbs, legumes, etc., in the sward and managing grazing practices, but mineral supplementation needs are going to be driven by local soil conditions, forage species (for example, orchardgrass is better at extracting copper from soils than is tall fescue), stage of growth/pregnancy/production (calcium and magnesium needs of lactating cows, etc.), etc.
But... at some point, most of us run out of available forage material for grazing, or weather conditions end the growing season, etc., and we're relegated to feeding stored forages (hay, silage, baleage, etc.) and grains/co-products/commodity feeds, etc.
Hay tends to be the 'base' for most beef cattle overwintering... but if you don't test your hay, you have no idea 'what's in there'... and all hay is NOT created equal. Believe me.
There are some very useful 'plug and chug' ration balancers online, like CowCulator, UofMN's, ration balancer, etc. You can plug in variables such as TDN, CP, ADF, NDF, etc. of your hay, established or customized values for supplemental feedstuffs, breed/frame score/BCS/stage of pregnancy/laction of cows, how much BCS you're willing to allow them to lose, etc. These can be used to determine how much hay, how much corn/ddg/cgf, etc. you need to feed to meet minimal or optimal dry matter, energy and protein levels.
Sorry, Stick... licking rocks is NOT going to provide minerals(and yes, I'm sure you were kinda tongue-in-cheeking it). Heck, they can't even get enough of most of what they need licking one of those red 'trace-mineral' salt blocks. Not to mention that in some parts of the country, even if they could get something from 'licking a rock' when they're deficient in something... those rocks are most likely deficient in the minerals they need... like selenium, copper, magnesium...