Studio Reference Monitors are designed to expose everything, whereas speakers are designed to be a pleasant listening experience. If there's anything a little problematic, you need to be able to hear it. Of course the more you spend, the more apparent these problems become.
Many years ago when I was a teenager, hanging with my friends in my room, something happened that shaped my opinion on singing forever… I attempted to sing one of my favourite songs, accompanied by my friend playing acoustic guitar with a small audience of two or three people. One of those people will today serve as an example of what not to do.