This approach is incredibly effective, and will almost certainly guarantee one of the infamous "question mark" emails gets sent out. There's a whole process built around question mark emails that drags in a bunch of senior staff to ensure things get resolved.
You can read about it here: https://www.inc.com/business-insider/amazon-founder-ceo-jeff...
I've been on the receiving end of an ajassy question mark email once. That was an interesting way to spend a few days. The customer was complaining about slow uploads to the aws service I worked on. All I had to go from was their country, via some guesswork. They did at least mention which region it was they were having issues with.
It took a bit of effort but I was able to prove from service logs, to a reasonable degree, that the problem was with their ISP. All I had to go from was what country they were in, didn't know their ISP, which added to the fun.