It has occurred to me that one reason people think they need to save a bajillion dollars to retire is that financial advisors, mutual fund salesmen, and your employer's 401k administrators are taking so much out in fees. Those high, unjustified, fees are then used to justify recommendations to save huge amounts of money in order to retire, which of course makes them more money in the long-term.
If you hire a financial advisor who charges you 1% of your invested assets every year to manage your affairs, and he recommends actively managed mutual funds and individual stocks and you end up paying another 1% in mutual fund and broker's fees, then you are paying 2% each year to have someone manage your money. He will also recommend an accountant, tax lawyer, estate planning lawyer, and insurance salesman on top of all that (who will in turn refer work back to him). 4% SWR is meaningless in this conventional retirement scenario, because you're paying half of your portfolio's income potential to financial professionals rather than using the money to buy groceries and trips to Machu Picchu. To fund all that, the financial advisor has to tell you to save $4M minimum to retire, knowing that you would otherwise risk running out of money paying for his kids college tuition. Compare with investing in Vanguard total stock market, which charges something like .17%. A MMM-style retiree avoids all this nonsense and therefore can live off of 4% - .17% = 3.83% of his or her savings.