Even after Linux became more than viable for dev boxes, it still had rough edges for laptops e.g. sleep, suspend, battery life, wifi etc. This was excacerbated by laptops often being weird one-off productions rather than a big box full of standard parts (and that you can assemble yourself if need be). There are other issues (using Microsoft Word and Adobe products, classy looking hardware) but I think for a long time that was a major factor.