Microsoft Office has long supported HTML but it also supports embedded objects. Word, for example, can even be exported to HTML using a complex embedded style sheet.
Excel charts can also be embedded as is seen with occasional posts on storage issues. One table is group by operating hours which tends to be right censored as older lower capacity disks are swapped for larger ones. Some disks have been in use for long periods of time primarily as the industry has been slow reducing $/TB for media.
Before the site migrated to WordPress there was a large assembly of HTML documents which were edited with Microsoft Expression Studio.
Embedded Excel allows for dynamic data which is one of the ideas used widely in corporate offices globally.