I have heard the same, but I still question whether it is one of those urban-myths....
When, for instance, you grow tomatoes, one type of fertiliser will stimluate vegetative growth, whereas another will stimulate flowering. Nothing to do with stress. What is really happening is that the plant is looking for optimal conditions for its seedlings to grow in.
Stressed plants do produce flowers out-of-season, but I would not make the leap that the means to achieve flowering is to stress the plant - it can only be a bad move. To anthropomorphise for a moment, if I were a plant, I would not want to produce lots of seedlings in an area already full of my own roots, but would rather produce them in an area where they had good soil and plenty of space for themselves.
For sure things like strelitzeas and figs do wayyy better when pot-bound, but I don't see any reason to assume that this is a general rule.