could diagnose most maladies with a simple blood test.
Theoretically you could replace destructive tests with nondestructive ones and do every blood test on a single sample. That's at least possible.
The real snake oil was the tiny sample. Some conditions have markers so small they may not reliably even be present in a tiny sample. If you have a false negative of 5% for these conditions in a standard sample and you take 1/100th the blood you could have a 90% false negative rate or worse.
Theoretically you could replace destructive tests with nondestructive ones and do every blood test on a single sample. That's at least possible.
The real snake oil was the tiny sample. Some conditions have markers so small they may not reliably even be present in a tiny sample. If you have a false negative of 5% for these conditions in a standard sample and you take 1/100th the blood you could have a 90% false negative rate or worse.