Why is it common for websites to wait for 5 to 10 seconds after clicking a download link before the download actually starts? They usually not show a countdown, and give a clickable link that starts the transfer immediately. The accompanying text might say: "If your download doesn't start automatically, click the link, or select another mirror." If I do click the link, I usually get a second download started after a delay. It is not those sites where you have to pay a subscription to get high speed, but regular open web servers.

To annoy you, so you would purchase a "premium" account, simple.

Or just to force you to make an account (a "free" account), so they can track you more easily!

Here's an example of such site.

https://www.opensubtitles.org/en/subtitles/

I know about shady sites that require a premium account, but these are not among them. There you usually have to wait 30 to 60 seconds.

For example on SourceForge, there is a circular counter that goes from 5 to 0 and then the download starts. You can also click on Problems Downloading directly. On ModDB you see a white box with a clickable link. Having an account on these sites doesn't bypass the intermediary dialog.

9 hours ago, j7n said:

that goes from 5 to 0 and then the download starts

Did you try to open the browser console to see what happens?

Maybe five seconds is more than enough to make a good fingerprint, including clientrects and canvas?

I presume it is to show ads. For Nexus (the modding site) it is to show you the donation message.