i think its a common rookie's mistake...
i have some experience in desktop publishing.
current industry standard is Adobe Pagemaker... some businesses and
organizations are gradually upgrading to Adobe Indesign though last
i checked, not that many of them use it yet...
either way, both are not your typical word processor 
in MS-Word, u just let 'er rip and it automatically moves to a new
page after u reach the end of one page... in these desktop
publishing software, u don't.
with Adobe, u basically have to define the number of pages your
publication will have at the beginning, or insert new pages as u go
along... both are not very intuitive processes.
the likelihood of a rookie opening a new document for every page is
rather HIGH... i've seen it happen myself... its quite tragic...
this kid i worked with (not his fault lah... he was only temp-ing
during hols...) actually had a 15 file document once... which
shocked me cos each file could actually accommodate, if i'm not
wrong, up to 9999 pages... or until your comp crashes from lack of
ram, whichever comes first... 
so if one pagemaker file = one page, the most automatic thing for a
rookie would be to output one pdf file for one page... its the only
way the work can flow smoothly...
also, with PDF, if u want a manageable, small file that displays
reasonably well, u HAVE to apply some compression. the temptation
is often to output the PDF in the highest resolution available...
that makes for a ridiculously LARGE pdf file... which is stupid cos
laser printers prints max 600dpi... 150dpi is usually relatively
good print quality for a laser printer already...
and if no compression is applied to the output file, be it zip or
jpeg (yes, PDF supports compression in these standards as well,)
u'll end up with a file too big to be useful for
mass-distribution...
for me, i usually experiment a bit with different settings if i
have time to get the best results... its a bit tedious, but the
output is well worth the effort. esp when u work with graphics, u
never know how the compression screws them up! double checking is
better than looking stupid when pple complain about the quality of
your work...
so u put these 2 childish errors together, u'll end up with their
shoddy work lor... very LARGE pdf files and one page per
file...
either that, or it simply shows that the organization has a very
twisted, convulated, inefficient way of doing work... like 20 pple
asked to do one page each to save time 
didn't even occur to them to join the files together
joining them would've reduced the file slightly as
it'll be getting rid of some redundant elements that defines each
page as a separate file...
yes, even if u made the first stupid mistake, it is technically
possible to join separate pages into one PDF file with several
pages... though it won't make much diff cos the output file will
STILL be too large for effective mass distribution... unless
everybody was using broadband...
now, doesn't this bring back memories of the times when Sg
digitized the documents and posted them as PDF files? they
actually said PDF files can be doctored as they are not scanned
images of the original files... i laughed out loud at that
cos it just shows that they don't even have the most rudimentary
understanding of the technologies commonly used today...
thats why it doesn't surprise me that they made a mess out of this
publication.