Certainly providing civil and governmental stability was an important factor in encouraging growth, but it is also important to remember that in Japan, as in Germany, this stability was also bolstered by billions in US aid and investment. The Korean War was also a big initial engine for growth in Japan as the US and its allies in the UN used it as a base, facilitating rebuilding projects.

I would say that it did.  The occupation set Japan up with a new political system that did better than its old one in terms of keeping more of the people happy and making them feel that they had a stake in the system.  This led to the political stability that was needed to allow Japan to recover in the coming decades.