Most of the capital invested in incandescent technology was related to the Phoebus cartel. The pressure to make incandescent efficient was just never there until very recently.
LED has severe problems, some solvable, some not. The article mentions flicker, but really should have specified. Nearly all LED drivers employ PWM. There are constant current LED drivers, and they are more efficient than PWM drivers, but PWM drivers are cheaper to design and manufacture. While many will claim PWM doesn't bother them because they can't detect it, they're not only exhibiting callousness for those that are bothered and harmed by PWM, they're falling into a fallacious trap, i.e. what they don't know and can't detect can't harm them, which is patently false, and one counter example is carbon monoxide. PWM LED drivers are now ubiquitous, and its effects range from annoying to painful, as anyone that has experienced migraine can attest.
Regarding the actual light LED produces, nearly all LED available are weighted towards the blue spectrum, and this light has been shown to massively mess with wildlife and shorten human lifespans by years by disrupting circadian rhythm, which strangely can lead to diabetes and heart disease.
LED proponents are obsessed with brightness, but this is also a trap, because brightness is not as important as what can be seen. Consensus among lighting and eye experts is that more can be seen with a dimmer light that reproduces color perfectly than with a much brighter light that does not.
As these issues with LED are mitigated, the drivers become more expensive and the LEDs become less efficient. And as the article mentions, the phosphors of better color-producing LEDs will fade rather quickly and over time no longer reproduce colors accurately. And let's realize that the best LED can ever achieve, what the technology has always been striving for, is to perfectly match what incan does with little to no development. Maybe someday LED light will perfectly match incan light, but it is not today and it isn't next year.
What it starts to look like, if the trend can be detected, is that as we fully mitigate the problems of LED, the more expensive it becomes until its cost and durability nearly reaches parity with what we already have with incandescent. It's starting to become a wash.
So unlike LED, if incan can be made more efficient, and there is a massive amount of room for improvement in efficiency there, then incandescent undoubtedly will return and dominate the lighting market. I liberally estimated 20 years, but it may take longer, but it really doesn't matter to my major point, which is that incandescent is coming back, and this is a very very good thing, because LED light, as efficient as it is, still absolutely sucks.