I was googling the origins of the typical focal length ranges of zoom lenses we have today for 35mm cameras i.e. 16-35mm, 24-70mm, 70-200mm and didn't really find anything.
Those ranges are incredibly inconvenient for me and there's very little alternative. Sigma makes a wonderful 50-100mm zoom but it's for crop cameras. If I had a 50-100mm zoom for full frame that would cover 95% of my portrait shoots. Similarly I hardly ever shoot wider than 20mm, so a 20-50mm zoom would cover 95% of my landscape shots. One lens. Instead I have to swap lenses and lose time and/or gain sensor dust, it's stupid.
Who picked those numbers and why? Is it a case of someone doing it first just because and everybody else following it blindly? A 2-2.5x zoom should not be that challenging to design and manufacture with good optical quality for reasonable price.