Face to face that’s very likely to be true, but online interactions are a bit different - in fact that would be like arguing that using real names leads to a better behavior VS an anonymous nick (and that that has been proved untrue is probably the greatest achievement of social networks)
Rather, there is a psychological mechanism that leads even perfectly OK people to stereotype others when they’re in a crowd, put them in some kind of large mental bin: since they’re hard to tell from on another they stop being a person.
As soon as there is a chance for less anonymized contact, this often reverts. This mechanism is easily observed e.g. in traffic: since vehicles tend to create a divide, stereotypes are assigned off superficially observations.
e.g. young lady or small car = can’t drive isn’t much different from got killed = n00b.
I have been stereotyped myself as a new-ish member of this forum, and I’ve been guilty of stereotyping occasionally.