Timwi-
Because we need to do manual numbering anyway, to keep the numbers consistent with those used by the auto-numbering for headers (which is a user preference).
Will this numbering ever be different from that of ol/li?
Not sure if we can get 1.2.3 formatting with <ol> at all. In any case, the numbering is different with inversely nested headlines (a higher level being introduced after a lower one).
Also, it was easier to get all the margins right and avoid unnecessary whitespace this way.
The major reason I want to use <ol> is because if you have a really long heading, it will render like this:
1 This is a really long heading
We can use the table to fix that. <tr valign="top"><td>1</td><td>Heading</td></tr>. Then we can also put the link on only the heading text.
Regards,
Erik