Please note: I did not read the underlying article.

All else equal, as price goes down expected return goes up. Therefore, it is reasonable that future returns post an initial -10% may be high enough such that you hit your average return over the long-term.

If you can suffer short-term forecast errors patiently and not over-react or even react to this noise then you should hit your long-term goals. It's the people that don't just sit there and do something that end up buying high and selling low. For these people it is quite obvious they won't make the mean return. Volatility is only a risk if you let it.

For instance, say you find a business capable of returning 10% on capital employed for the foreseeable future and you buy it at what appears to be a very fair price. Now, this is hypothetical of course, the average underlying return line is straight with each year successively higher. Since this business is traded the actual stock price will experience volatility such that the return in any given year is above or below that 10%. A good investor would add to their position in years when the return is below 10% and sell pieces when the return is over 10%. So that over a long-term horizon the return achieved is basically 10%. It is the investors job to not let the changes in market price confuse them into thinking that the market is always accurately reflecting the changes in true value.

As far as the point about sequence risk is concerned it would reasonable that a properly allocated portfolio mitigates the problem of having to sell low in retirement to meet income needs. It would be of little issue if the overall portfolio drops 5% in the first year if you can sell stable assets that did not decrease in value. The remaining assets are thus the major contributors to the negative performance which you leave invested. This re balancing, if you will, enables the investor to hit those averages.

The problem which I believe you are addressing only makes sense if you hold 1 asset in your retirement account. For example a 2017 target date fund.