Today (2nd December, 2020) the authors have updated this plugin. As its name suggests it disables the opportunity for visitors to comment on your posts and pages. It is not selective but switches off all comments. If this is what you want because you keep forgetting to set the option when writing a page or post, it will be useful to you. It is a duplication of a built in option with WordPress so on the basis that a website should have as few plugins as possible you might want to think about whether you should install it.