> convincing the European Commission in 2014 that there is no technical way to integrate Facebook Messenger and WhatsApp user accounts.

What was the argument there? It's not like that's solving the halting problem.

I think “technical” here just means something like: one uses phone numbers and the other uses emails. The current technical solution doesn’t make it straightforward to merge. Evolving the technical solution would require product and user facing changes. And probably a lot of edge cases

That sounds like a tech interview question

I am not sure why a shared messaging infrastructure implies merging accounts is easy/possible. It's fully possible to have messages pass on a common infrastructure between different entities that correspond to messenger/whatsapp accounts.

I'm not saying I necessarily believe facebook here, but I don't understand how they are contradicting themselves here.