

Not necessarily traffic. Often download sites use mirrors to serve you the download. Sometimes those links are provided via a CDN which can be forced to comply to LEA or some other static hosted mirrors which are often hosted by others. The second part is more likely on community managed software.
So either traffic or the server/CDN behind the link. Happened before.
Most critical infrastructure like my mail i subscribe to the release and blog rss feed. My OSs send me Update notifications via Mail (apticron), those i handle manual. Everything else auto updates daily.
You still need to check if the software you use is still maintained and receives security updates. This is mostly done by choosing popular and community drive options, since those are less likely to get abandoned.