Former barista here! This is what that is. Different machines using different roasts, water, settings, etc. will extract differently, resulting in different oil amounts.
It definitely might, water chemistry changes extraction so much there are coffee nerds who add tablets to distilled water to get the right composition to brew with.
Whatever your thoughts on that is, distilled water is not optimal if you want to extract coffee.
Water chemistry makes a lot of sense. Coffee is like 99% water (a number i pulled from my ass, but its definately more than 90%).
And considering i can taste the difference between (say) san pellegrino (fuck nestle) and a more generic sparkling water, i can imagine water chemistry being important.
I know beer brewing takes it very seriously, tho perhaps beer has more delicate flavours and more long-running biochemistry.
Is it worth it for a single cup of coffee? For me, no! Because i make trash coffee.
But for someone that has spent $$$$$ on a coffee brewing setup, has roasted their own imported beans and has horrible tap water... I can understand them using distilled or RO filtered water, then customising the salts.
And I can imagine some coffee-interview talking about "their process", digging into the water chemistry thing, and it becoming more widespread amongst enthusiasts, regardless of tap watet quality