There's such a volume of lost plays. Athens held annual festivals where you'd have perhaps 20 tragedies and 5 comedies over 5 days[1]. That's just one city state. Only 32 full plays survive.
Edit: Reading the article, I'm surprised they don't seem to have done any computer-based textual analysis of the authorship. We have other plays attributed to Euripides so matching 98 lines of text shouldn't be too difficult.
[1] https://en.wikipedia.org/wiki/Dionysia
Edit: Reading the article, I'm surprised they don't seem to have done any computer-based textual analysis of the authorship. We have other plays attributed to Euripides so matching 98 lines of text shouldn't be too difficult.