[johnnyo]

I don't run a German website, so I can't give you exact numbers, but in my experience, software can often default to something like 'en-US' in a variety of cases where you might not expect it to. This is especially common in poorly localized tools. For example, a poorly implemented browser component inside some other tool or phone app might not properly set this value, and instead default to en-US.

Switching to the proposed method might fix the author's problem, but create a bunch of problems for other users in other scenarios.

[imedadel]

Not sure about German-speaking countries, but in Francophone countries, everything is in French. Even if the default is English, the user would insist on switching to the French version.