It certainly will work. A couple of years ago, a young person who "helped" me one day in the garden, split one of my then-18"-tall tomato plants in half. The planted portion, I left in the ground and watered it extra much (yes, I know "extra much" is not really a word combo), the other went into a bucket of water. Not only did it root, but when planted, it provided a good crop. While it has been my intention to do such a thing later in the season and plant the starts for a winter crop in a protected area, I've not yet done it. Your post may inspire me to actually do it this year. :-)
If I could be certain it would always work, perhaps I'd cut my plant purchases in half. LOL
Glenna