When strictly speaking, chocolate is any product 100% based on cocoa solid and/or cocoa fat. This is because it is used in a vast number of by-products, any change in the cost of making it has a huge impact on the industry. Adding ingredients is an aspect of the taste. On the other hand, reducing cocoa solid content, or substituting cocoa fat with a non-cocoa one, reduces the cost of making it. There has been disagreement in the EU about the chocolate definition.
Some want to see the definition allowing for any cocoa solid content and any kind of fat in chocolate. This would allow a merely coloured and flavoured margarine to be sold as being chocolate. In some countries this happens, and a 50% to 60% cocoa solid dark-chocolate, with no additive, for domestic use, is hard to find and expensive.
Others believe in adhering more strictly to the definition above.