When sites get rewritten companies often delete obsolete models.
However most will happily sent you a PDF .
They are just living in the past when web server space was expensive so priority is given to lush full colour adds & brochures.
It is dirt cheap now days to run your own web server for things like archive materials but even now 99 % of managers are computer illeterate.
The proof of this is all the companies rushing to put their data in the cloud hen wondering why it gets hacked , hyjacked or ransomed