Maybe because a semicolon is valid in URLs. Although the top answer on stack overflow also says: "However, if you're plucking them from relatively unstructured

Maybe because a semicolon is valid in URLs. Although the top answer on stack overflow also says: "However, if you're plucking them from relatively unstructured prose, it's probably safe to assume a semicolon at the end of a URL is meant as sentence punctuation." Because you can never know how a given website will handle the input, I always leave a space after URL and before punctuation in a text box, like so: http://example.com http://example.com ;