In general, there are two sources that improves productivity in Engineering: tooling and architectual design. Effective tooling for software development can only make an Engineer 2 to 3 times more productive than the average. When we talk about 10x Engineer, we are most likely referring to the productivity gains from making right architectual decisions. From a business perspective, it could literally save months or even years of work.
The maximum productivity of an Engineer is in reverse ratio to the size of the company. We all know that the more people a company has, the harder people from different teams can communicate with each other. Therefore, large companies tend to be much slower in delivering features than nimble startups. However, is individual engineers being unproductive at work a bad thing for a big company? Probably not as bas as you think. Big companies value predicability more than productivity because they want predictable business outcome and avoid mistakes in expense of productivity.