Despite the credentials of the author, I don't find that excerpt very convincing (although she may shore up her argument better in a longer piece). For example:
Very little attention was paid to the possible connection between the fictional Count and his historical namesake until 1972 when Radu Florescu and Raymond T. McNally’s In Search of Dracula revealed to the world the story of the real Dracula – Vlad Tepes.
Yet later she writes:
Investigations into possible connections between the Count and the Voivode began before the publication of In Search of Dracula. In 1958, Bacil Kirtley stated that “Unquestionably the historical past that Van Helsing¼ assigns the fictional vampire Dracula is that of Vlad Tsepesh, Voivod of Wallachia” (14). In 1962, Stoker’s first biographer, Harry Ludlam, asserted that Stoker had “discovered that the Voivode Drakula or Dracula … had earned for himself the title of ‘the Impaler,’ and that the story of his ferocity and hair-raising cruelty in defiance of the Turks was related at length in two fifteenth-century manuscripts, one of which spoke of him as ‘wampyr’” (113). In 1966, Grigore Nandris connected the vampire Dracula with the historical figure, even claiming that available portraits of Vlad were “adapted by Bram Stoker to suit his literary purposes” (375).
This all seems directly to contradict her initial assertion.
I'm not arguing that Stoker was a meticulous researcher or even that a novelist would want to make a fictional character conform exactly to a historical figure (especially not a character of gothic fantasy). But I think that it's more attention-getting to make strong claims in academic research such as "Stoker didn't base Dracula on Vlad Tepes," rather than something narrower, such as "although Vlad the Impaler was major influence on the character of Dracula, Stoker used a lot of resources and probably got a lot of things wrong. He also took a great deal of creative license."
What I gather from reading that is Stoker likely had the idea for a vampire book before he heard of Vlad the Impaler, but once he did hear of the historical figure, he realized that the folklore associated with Vlad would give him a lot of material to make his novel and character more interesting. Most critically in terms of the dispute, it is where Stoker got the name.
She does have a lot of publications regarding Dracula and quite the recognition for it as well, I don't think the article is an attempt at getting attention by throwing around a controversial topic. I know very little regarding this subject as I just read the original book, and a translated version no less, and none of the biographies or any other research on the subject, but I believe in the first quote you linked, she refers to general public, this idea that Dracula was based on Vlad Tepes becoming part of the popular culture, while the previous ones did not lead this to be part of the popular culture.
For my part, I found her argument regarding Stoker's encounters with Arminus Vambery and regarding his research in the British Museum archive to be fairly convincing, and it is very much true that Count Dracula is a character very much in line with the Gothic tradition he is a part of and follows most of the tropes that were already in place when he was written. I am not entirely convinced that he was or was not inspired directly by Vlad Tepes, and I admit that most of my knowledge regarding the subject comes from this article, but I am leaning towards the side of the article, and I found the article to be quite an entertaining read and quite interesting in content as well, which is the main reason I linked it.
I would love to discuss more in detail, but this is about the extend of my knowledge regarding this topic and all I have to contribute to the discussion. My personal reading aside, I think the article is very much worth reading whether you agree with the author or not.