Three legged stool - metaphor mixup

This week, Gil implied Social Security was devised as a "three-legged stool".

Social Security was never meant to be the sole means of retirement; it was supposed to be one leg of a three-legged stool — the other two being private pensions and savings and investment. Read more

However, this metaphor is not attributed to the Social Security Act and actually came about 14 years later. How did I find out? I had to look no further than the Social Security website which states:

President Franklin Roosevelt is not the source of this metaphor, nor was anyone else associated with the creation of the Social Security program in the 1934-35 period. The earliest use of this metaphor which we have been able to document was by Reinhard A. Hohaus, who was an actuary for the Metropolitan Life Insurance Company. Mr. Hohaus, who was an important private-sector authority on Social Security, used the image in a speech in 1949 at a forum on Social Security sponsored by the Ohio Chamber of Commerce. Source

Is the metaphor a good one? Arguably, it COULD be. The Social Security administration seems to think so. But to imply this was the idea from the start is certainly a stretch to me. The bill wasn't even called the "Social Security Act of 1935" at first. It was originally titled the Economic Security Bill. It covered other issues besides retirement, too. So to single it out as just part of a retirement plan is a narrow idea of it.