Cooking is bishul, not boneh. So how are you demonstrating a heter for boneh?
Are you allowed to build a kitchen in Yom Tov? Of course not. But you are allowed to cook in a kitchen which was built prior to Yom Tov, using an electric burner which was turned on prior to Yom Tov, because you haven’t done any binyan.
To clarify, the issur of electricity may not be boneh d’Oraisa, but my point is valid nonetheless.
Again, the vast majority of poskim, for whichever reason, asser electricity not only on Shabbos, but on Yom Tov as well, and this is now the universally accepted psak.