One of the big reasons is that developers don't want to be locked in to something. The tool itself needs to be significantly better than the free competition, w

One of the big reasons is that developers don't want to be locked in to something. The tool itself needs to be significantly better than the free competition, while still being able to easily pull it out and replace it with something else on short notice. Startups don't generally like those rules, they tend to thrive on lock-in and controlling the users for a chance of a big payday. I think developer tools are generally fit more of a "lifestyle business" than a startup.