Diseases were vestigial in 2014. They only existed because curing diseases has always been a thing paladins could do. But if there was a paladin in the party, diseases were trivial to cure. So, the entire exercise just felt like a weird pantomime where DMs were including diseases just to humor the Paladin player, and Paladin players were spending 5 points of Lay on Hands to cure diseases they knew only existed to humor them. By getting rid of diseases as a specific codified category of thing, we are free of that silly artifice. Now, diseases can still exist as bespoke game constructs that include their own rules for how they can be cured, and they can therefore always be as easy or as difficult to cure as the narrative demands.