Scheme is a ... practical language.
Really? Relative to what? Even COBOL was more practical than Scheme can ever hope to be. The label of "practical" belongs to the likes of Java and Python, not to Scheme.
After nearly half a century of being showered with the attention of intelligent people, Scheme still does not have a vibrant portable library ecosystem. There is no portable library for building web applications. Its implementations are still splintered among numerous incompatible mini-dialects. Scheme's long life is a testament to its ability to survive in the educational toy niche. It has yet to move beyond toy status to become a truly practical language on par with Java and Python.