"There are a lot more startups today, and you can in effect become an early investor in one by going to work for it."
It's important to remember that she means this for one very particular industry, and she is talking about a very particular kind of startup. Overall, there has been a steady decline in the number of startups during the last 30 years:
https://www.fedinprint.org/items/fednsr/707.html
"The first observation is the steady decline in the firm entry rate over the last thirty years, and the second is the gradual shift of employment from younger to older firms over the same period. Both observations hold across industries and geographies."
The great era of starting a new business in the USA was several decades ago. It is much more difficult to do so now, and that is perhaps part of the reason why there are less entrepreneurs now, and less new companies being founded.