Your logical fallacy is no true scotsman.
You made what could be called an appeal to purity as a way to dismiss relevant criticisms or flaws of your argument.
His counterpoint is valid. React only serves to slow down "real" projects that consist of UI components that aren't simple (more than a todo app). How? By using React you inevitably add the steps of maintaining its ecosystem, researching its documentation, and relying on Facebook for their duplicate version of HTML, CSS and JS.