We probably haven't lost as much as you think - we either still use it or it was bunkum (for a given application).
eg. Chamomile - still used for bad stomachs (is a costive), whether it works on herpes simplex seems really dubious.
eg. Chamomile - still used for bad stomachs (is a costive), whether it works on herpes simplex seems really dubious.
Often modern medicine is based on these plants. And of course there are modern treatments that go way beyond what we were able to achieve with just plant-based medicine.