You want diversity of bugs for a healthy garden. The fewer bugs present the more input and care it will require, and the easier it will be for an infestation to occur. You're having to do the bugs and other critters work of fertilizing, keeping each other in check, pollinating, etc.! I have seen this theory work in my garden, as I follow permaculture principles and grow polyculture. I get advice and learn a lot at permies dot com.