Tomatoes are not all vines. They can be bush (determinate) or vine (indeterminate). Determinate means they grow to a ceratin size and produce all their fruit at once. while indeterminate means they keep growing and fruiting. The vine/indeteriminate can be cut back severely and grow. They do not just grow from the tips, but if severely pruned with grow from the base. As a matter of fact they are one of the few plants that should be buried deeper when transplanting than they were previously, as they will push out roots from the stem for a healthier and stronger plant.
