Wow, that was a really bad article.
Let's debunk every one of their issues.
Let's start with the fact that the rule was created more than 20 years ago, when interest rates were higher. In such an environment, the bond portion of a portfolio would have been generating more income. We've been in a low-interest rate environment for a long time now, rendering our bonds less able to replenish funds withdrawn each year.
100% irrelevant. The 4% rule wasn't based on the market conditions of the time, but the history of the market over decades. It encompassed wars, depressions, recessions, etc. It has nothing to do with what interest rates were in the 90s.
Then there's the rule's assumption that your portfolio will be split 60-40 between stocks and bonds. You might not have or want that allocation. If your portfolio is split 50-50, or you have 75% of it in stocks, then the 4% rule won't work as advertised.
Mostly irrelevant. Yes, AA is important. Minor tweaks like they mention won't shift the 4% rule much at all. Anything between about 30/70 and 70/30 have very similar outcomes.
Meanwhile, many people are living longer. Datafrom a 2015 Centers for Disease Control and Prevention report shows that those born in 2014 can be expected to live, on average, to age 78.8, up from 75.8 in 1995 and 70.8 in 1970. And those are just averages -- many people live much longer (and some much shorter) lives. The 4% rule aims to make your money last for 30 years, but if you retire at 62 and live to 96, you might be quite pinched in your last years.
This is the only semi-valid one, but you can, you know, plan for this (and especially see, after a few years, the direction your portfolio is trending--if it grows, and thus your WR based on current portfolio size shrinks, you're very likely to be able to have it last 40, 50, 60 years or even indefinitely).
Finally, remember that every set of 20 or 30 or however many years in the stock market will be at least somewhat different -- some with higher-than-average gains and some with lower-than-average gains. If you plan to follow the rule and withdraw 4% of your nest egg in your first year of retirement, what if the stock market and your portfolio tank by 30% in the year leading up to your retirement? Such things can happen -- the S&P 500 plunged 37% in 2008. If that happens early in your retirement, you'll either be withdrawing far less than you'd planned on or you'll be depleting your nest egg faster.
100% irrelevant. If the market drops the year before you ER, you haven't hit your number, and don't ER. If it drops the year you ER, well, that's accounted for in the 4% rule.
Their criticisms are bad, and they should feel bad.
There's legitimate reasons to be (a little, not much) concerned about the 4% rule. Longevity is MAYBE one. The rest? Total bunk.