Haven't read (no access) the article, however stocks are not guaranteed to see price and/or income pace or exceed inflation and can/have seen significant broadly progressive declines even over 20+ year periods. If one has £50K in cash now that is sufficient to cover the next 5 years of spending, perhaps supplemented with a £20K/year occupational/state pension (£30K/year spending lifestyle), and one wants another £50K of inflation adjusted capital to become available in 5 years time, then a inflation bond priced to a -2% yield requires £55K present day money to pretty much guarantee that.
Fixed/guaranteed income is a preference for some and no other asset provides the same level of assurance. Whilst in the present era that guarantee 'costs' (negative real yields), in other periods real yields are positive ... broadly washes.
If in addition to that £105K of cash/bonds the investor also had £150K in stocks, then after the ten years across which all of cash/bonds had been spent then at around a 4% annualised real return stock value accumulation rate they'd end the 10 years with similar inflation adjusted capital value as at the start. Rather than starting with £150/£105 stock/bonds, near 60/40 stock/bond proportions, ending ten years with 100/0 stock/bonds, that averages 80/20 stock/bonds, some instead prefer to just direct (yearly rebalance) to that 80/20 average stock/bonds ratio - to likely equal/similar effect. US data indicates the differences between
80/20 and 100/0 are just noise of differences.
Yet others prefer gold to bonds. A 50/50 stock/gold barbell is in some ways similar to a 50/50 1 year and 20 year treasury bonds (Gilts) barbell, both combine to a central 'bullet', a 10 year bullet in the case of the 1/20 year bond barbell. Which reflected into the above equates to a
90/10 stock/gold asset allocation - again just noise of differences.
Drawing £5K of inflation adjusted income from £255K of capital/assets is a near 2% SWR (safe withdrawal rate), that is more inclined to be a perpetual withdrawal rate (PWR) i.e. last forever (outlive you and leave a inheritance). Which again for some (who wish to leave to heirs) might be more preferable than the only other relatively safe choice of buying a annuity that tends to leave nowt for heirs.