Not only that, I have to question the author's arithmetic and use of statistics:
"Since 1871 in the U.S., all 40-year periods (there were 89)"
2001-1871=130
130 div 40 = 3 -- count 'em -- 3(!) statistically independent samples.
Please read carefully paragraph 8 and especially Table 3 at this site.
These are rolling 40-year periods. There were, in fact, 89 of them during the period discussed since 1871.
-'Copernicus'
my user name on FR is rimini, but I, 'Copernicus,' am the author of this set of "Social Security and Stocks" articles. Thanks for your vital interest.
P.S. The expansions of the financial--and all--markets are without limit. What appear to be limitations and restrictions are transient episodes of contraction, soon followed by expansions. See Market Timing.