There is not much value to be gotten out of creating Jinja blocks and
appending them to a list when nothing particularly interesting is done
with the list. With changes to move more towards semantic HTML, as well
as more ease of access to data in the template engine in the new code,
it is preferable to leave block division to the page template by making
it a property of the <section> tag. This also allows creating blocks in
Jinja iterators, which is not possible to do cleanly in the idiom being
replaced here.
