Rangers, Animal Companions, TWF, and the popularity of Drizzt are all the same topic. That's the point.
(But yeah, we got pretty badly off topic.)
Yup. Not only can DPR analysis can involve a huge amount of unspoken assumptions to arrive at the final number. But it also overlooks less tangible benefits and downsides. The upside is it's a fixed calculable value.
That appeals to a certain analytical mindset, and certainly is useful for disproving incorrect claims, like (for example) a claim that TWF holds up for Fighters after level 11. The downside is people often overly focus on it as the only thing of importance, since other factors are either incalculable or less solidly a metric of comparison.
However I think it's fair to say that comparing TWF to any other fighting style, when Feat support and multiclassing are on the table, just generally doesn't stack up well. Even considering the totality of all factors, those with easy metrics and those without. Except for Rogues. Its especially egregious for single class Fighters, who have it as an available Fighting Style.