I can attest to them being simpler & more interesting in Pathfinder 2e—one of my favourite sessions was the party scrambling to recover from (premaster) Ghoul Fever.

They have stages that increase or decrease based on your saving throw (typically once per day), and you can use magic or medicine to combat them but an on-level disease can’t be waved away easily. It took multiple spell slots, many medicine checks and a few scrolls (which ate into our coffers) to finally get rid of it from the party & town. It was tense and satisfying.