Hi!
I wanted an old portable version of Foxit Reader. But I couldn't find it here. So I had to download it from an unknown, unfamiliar website. I ran into this issue a couple times before.
Why even remove old versions? There are many reasons one might need an old version.
In which case a portable version is highly desirable, so that one doesn't mess up the configuration for the newer version of the same software that's already installed on the system.
It comes down to the difference in hosting between freeware and opensource.
With one notable exception (LibreOffice), opensource apps are hosted on our sourceforge project page. Old versions continue to be hosted there. Note, however, that in the case of browsers specifically, even if an old version is available, it should not be used due to potential security vulnerabilities.
Freeware apps, on the other hand, are hosted by the application publishers, or more often than not, self-hosted by us. As such, we (or more accurately, John Haller alone) are paying for each and every file hosted therein. Accordingly, we do not have old versions of freeware apps available, since we'd have to pay more and more for each file.
John will likely explain better, but that should give you an idea for now.
Aren't there free hosters where the files could be uploaded to?
There are specialized websites like oldapps.com, oldversion.com.
As indicated above, we do not, nor do we intend to, provide old versions of software when new versions have been released. With opensource software, we don't remove the downloads from sourceforge, so they are still available indefinitely. However, we keep our private download servers clean, so old versions of freeware are not available from there. Likewise, we do not then upload those files elsewhere, as we have no control over the files in any way, and cannot guarantee the authenticity of them.