JS front-end frameworks are born from ad hoc application architecture or from difficulty applying an existing framework to an application. The progenitor applications had different feature and development requirements, which is reflected in the varying frameworks.

While it may seem a plethora of frameworks exist, a few have most of the market share. That is not too far from the situation with other programming languages and framework types.

There are also old frameworks that have essentially been obsoleted but continue to stick around due to project inertia, the needs of legacy code, or marketing needs of the maintaining organizations.