It's important to note that opinions about technologies like ReactJS can vary, and what might not be worth it for one person or project could be beneficial for another. However, some common reasons some developers might find ReactJS challenging or not worth it include:

Learning Curve: React has a learning curve, especially for beginners. If you're looking for something quick and easy to pick up, you might find other frameworks or libraries more suitable.

Boilerplate Code: React can require writing more code compared to some other libraries, which may be seen as boilerplate. This could be seen as time-consuming or less efficient for smaller projects.

JavaScript Fatigue: React is often used in conjunction with a variety of other tools and libraries, which might contribute to what some developers call "JavaScript fatigue." Managing the ecosystem can be overwhelming.

Not SEO-friendly: React relies heavily on JavaScript for rendering, and some search engines might not index content as effectively as traditional server-rendered websites.

Overkill for Simple Projects: If you're working on a small project or a website with minimal interactivity, using React might be overkill. Simpler solutions could be more appropriate.