Oh, OK. (I don't think I've ever before encountered the idea that we benefit nature by having cut flowers in our homes.)
I'd always just assumed that flowers one buys are grown especially for that purpose and wouldn't have been grown otherwise. If that's so, it doesn't seem like having flowers around your house does much harm.
I have encountered it many times:) usually after I ask people why they do ..., they often ramble to the point.
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.