I never heard that either. I know people recommend putting sugar in your water for the tree, which is a bad idea, all it does it clog up the xylem which breaks the water column in the tube and then it's all done sucking up water
Not sure what the theory is behind sprite, but I imagine it is the same. They key to getting a tree to last a long time, cut it fresh and keep it watered. If you aren't cutting your tree fresh, or you're not getting it within a day or so of being cut, watering it doesn't make much sense. The water that you pour into the base is just evaporating.
I know nobody ever believes me, but I still say it
and still there's ten thousand websites telling you to water your tree, and unless it is fresh cut, it won't matter.
Water is pulled up a tree because of the bonds between water molecules, when that column is broken it can start again, in the roots. Since we don't have roots anymore, it can't. In the summer, water moves up a tree 4+feet per hour. This slows of course in the winter.
Considering a lot of pre-cut trees are cut in October already and then shipped, or at least weeks before they are sold, that water column is so far up the tree by the time anyone buys it, they'd have to cut off 6 feet or more of tree to get to it
Even if you cut your own and don't put it up for a few days, there's a good chance you're too late to get it in water and have it keep pulling up water.
Adding sugar doesn't do much good, trees make their own sugar, adding it just clogs the system.
At least that's what my plant bio professor taught me 20+ years ago.