It puzzling also because in a tech company, surely there would have been a large number of people with experience from various communities who would know people primarily by a handle, and realise that in many sub-cultures people would be unable to connect with people they know very well if they were forced to use real names.

There are people who have known each other for decades that know each other by e.g. demo-scene handle only. In which case their real name has an anonymizing effect to the people they want to connect to online.