Not sure if that’s true.

Looking at the history of modern medicine, the cure rate of diseases was not exponential, it was gradual over the course of hundreds of years.

Sure there were a few big jumps- water sanitation and antibiotics come to mind- but if you look at cured cardiovascular diseases, cancers, GI diseases etc., they all started with bad treatments that indeed slowly improved over decades.

If CZI is looking to eliminate all disease in a lifetime (say 100 years) I would expect some progress.

You're talking about curing diseases where each disease is a largely independent effort, which is distinct from an enterprise aimed at curing all disease. The former will be much more linear in appearance than the latter.