The code for Gutenberg blocks can often be considered problematic for several reasons. First and foremost, the block-based approach introduced by Gutenberg marks a significant shift from the traditional editing paradigm within WordPress. While this approach offers greater flexibility in page layout and design, the downside is that it can lead to complex and sometimes convoluted implementations of both custom and core blocks.
Overhead in Code Structure: With the introduction of React and JavaScript-based components, the underlying architecture of Gutenberg blocks can be intricate. Developers familiar with PHP may find it challenging, as the learning curve for React and modern JavaScript practices is steep. The complexity of using props, state, and component lifecycles can contribute to a perception of “horrible” code.
Performance Issues: Many Gutenberg blocks may not be optimized for performance. This can lead to longer load times, especially when multiple JavaScript files are enqueued for various blocks. Poor performance can be attributed to excessive re-renders and inefficient handling of components, leading to a sluggish user experience.
Lack of Consistency: Not all block developers adhere to the same coding standards or best practices. This inconsistency can result in poorly designed blocks that may conflict with one another or fail to integrate seamlessly. Blocks from different developers can also introduce redundancies or conflicting styles, which can be frustrating for users and other developers.
Limited Documentation and Resources: The Gutenberg framework is relatively new, and as such, the documentation and community support are still evolving. Developers may find it hard to access clear examples or best practices, resulting in implementations that are not optimal or easy to maintain.
Backward Compatibility and Legacy Code: Many users and sites still rely on older themes and plugins that may not be fully compatible with the block editor. This can lead to situations where custom blocks are created to bridge the gap, resulting in messy solutions that combine old and new coding practices.
Content Mismanagement: Gutenberg’s block system allows for extensive customization, but this flexibility can lead to content becoming disorganized and less maintainable. Users can end up with a mishmash of blocks and layouts that are difficult to edit or adapt in the future.

In summary, while Gutenberg blocks offer enhanced editing capabilities, the underlying code can often seem problematic due to complexity, performance issues, inconsistent coding practices, limited documentation, and struggles with backward compatibility. However, many of these issues can be addressed with improved practices and ongoing updates to the Gutenberg ecosystem.