I'm not sure that an argument from monoculture is the right way to go here. It's merely a form of security by obscurity, and probably shouldn't be the dominant

I'm not sure that an argument from monoculture is the right way to go here. It's merely a form of security by obscurity, and probably shouldn't be the dominant factor in whether or not you take some amount of mythical man hours to roll your own code vs. adopting a piece of very well established OSS that has had countless eyes on it over the years.