This is NOT true. If that were true, then we wouldn't have a single plant left in the wild because all the flowering VFTs who haven't had the Scissors Fairy visit for a snip, would be dead.
It takes energy for ALL plants to flower. It does not kill them. It may slightly slow the growth but that's no biggie. Cutting off a flower stalk is a purely personal thing. If you like the flowers, let it go. If you don't want seeds or flowers, cut it off.
Your plants will NOT die if you allow it flower. The source of your problem is most likely something else. Could be spring water. Spring or mineral water is not good water to use. It has a high mineral content. Rain, distilled or R.O. is what you need.