In other words: What pain?
Nor even was it when Skype and IRC were made (by Europeans). SMS (also European) was slightly harder to invent because that's not on the internet.
This is a response to a hypothetical where every single existing (or possibly just US) chat provider leaves the EU, and I'm saying the claim that this will cause any degree of pain whatsoever to the EU population is ridiculous because the replacements are far too trivial to not immediately replace the US apps.