Getting 100 to 1 returns doesn't happen overnight. It usually takes years, often decades.
Having a few exceptional growth stocks can work wonders for a portfolio. The best time to sell a great stock is possibly "never". (Meanwhile, the best time to sell an awful stock is "ASAP".)
The 1960's were a period of unprecedented growth. More 100-baggers came out in the 1960's than the subsequent decades. Having more time to grow was also extremely helpful.
Great companies were made in the 1970's and 1980's, too. It took a 1980's bull market to really get things going.
The number of 100-baggers from the 1990's started to decline for some reason. It could have have been the effects of a "lost decade" for stocks from 2000-2010. It is also possible that there are still many 100-baggers coming out from the 1990's and early 2000's - we just haven't seen them hit maturity yet. (Also, the cut-off date from the study was around 2010).
Financial regulation in the post-9/11 era meant that many companies started going public much later in their life cycles. This was fine for venture capitalists and unfortunate for individual investors (who started to miss out on some of the best opportunities).
But here's the most interesting thing....
The time that it takes to get a 100x return on top growth stocks appears to be shortening.
This requires a higher annualized rate of return on capital invested. Digital technology made this possible, along with network effects and automation.