Mary in KY,

you only need to read the site you posted:

"Many critiqued Dolphin's theory and noted that there was no evidence that drinking blood would help the symptoms of Porphyria."

That's one of the things that makes it weak. The only thing that people suffering from the disease REALLY have in common with vampires is light sensitivity--and in some cases, funny looking teeth.

One of things that's always a red flag is when something like Porphyria is first put forward as an explanation for reports of werewolves, then for vampires. This is an indication that it does not closely fit the traditional features of either. When looking for explanations of supernatural phenomena, too many so-called "skeptics" rely on bad descriptions of the phenomena themselves, thus allowing their explanations to look like the phenomena. This is another instance: werewolves and vampires traditionally do not look anything alike, but the same disease is advanced as a method for explaining both!