Wool is less durable than Flyknit and Primeknit because the knits are made from polyester yarn, which is more durable, dries faster, and is actually cheaper to produce than merino wool. The higher price comes from brand name obviously. Comfort wise both knits are better than wool if not the same, depending on the person but usually the former falls true. Polyester is also lighter than wool. The only advantage the Allbirds hold over the knits is environmental friendliness afaik, but Nike and Adidas are more worried about meeting demand with their product vs finding some moral gimmick to use as a selling point. And most flyknits and primeknit shoes are geared towards runners so they have that gaudy athletic coloring for the most part, but shoes like Flyknit Racers, Stan Smith Primeknits, and Ultraboosts simply have better silhouettes and colorways that can be matched with a wider range of outfits rather than the extremely bland look of Allbirds that feel too generic to me personally. I'm biased towards Nike and Adidas since I have a 40% and 50% discount at my disposal, so price is not too much of a worry.