I couldn't even begin to count how many bug reports I've seen over the years that start with "when I accidentally double-click foo, bar happens". It might not be an intentional usage pattern, sure, but that doesn't mean it doesn't happen a lot.

Google Drive uses it as an interaction pattern. I find that baffling, but while uncommon, it's not totally absent. And as others have pointed out, many users carry over their expectation of having to double-click from desktop interfaces.

> double clicking is extremely uncommon on the web so that would be a big red flag.

You've never had a slow internet connection have you? I've seen double clicking from all users in the office. Comes from frustration.

How many times have you tried to open an application; for it not open? So you click the icon again only for two windows to split open?

Young, old, even techs. It's not as uncommon as you think.

I double click to select text all the time. Get your flags ready.

Double clicking on the web is extremely common with older less technically adept users. This same cohort is also the most susceptible to scams.

Web browsers and the applications on them have become extremely memory hungry. Memory management pauses are common and people click multiple times irately.