Projects can have three plus build tools that each take a long time. Massive list of dependencies plus bad dependency management, lack of documentation, everything changes so fast you need to find the correct stackoverflow answer for this week solution to your build problems, build tools depends on other build tools configurations in undocumented ways, reimplementation of the model & business logic of each project, constantly reinvention of the wheel.
And the end result? Web just becomes slower and slower.
Developers today build software that fits their paradigm, not the users experience.