AsciiDoc produces nicely styled HTML directly without requiring a DocBook toolchain but there are also advantages in going the DocBook route:

• HTML from DocBook can optionally include automatically generated indexes, tables of contents, footnotes, lists of figures and tables.
• DocBook toolchains can also (optionally) generate separate (chunked) linked HTML pages for each document section.
• Toolchain processing performs link and document validity checks.
• If the DocBook lang attribute is set then things like table of contents, figure and table captions and admonition captions will be output in the specified language (setting the AsciiDoc lang attribute sets the DocBook lang attribute).

On the other hand, HTML output directly from AsciiDoc is much faster, is easily customized and can be used in situations where there is no website]).