This critique doesn't really make sense.
No matter how the person asks their question your flow is going to be interrupted the moment you open your chat apps. If the person says hello then asks a question a minute later your flow is broken. If the person asks the question right away now you're answering the question and your flow is, just as likely, broken.
As far as flow interruptions are concerned, it's not the fault of the person asking a question but rather the invasive design or reliance on chat, or your own patterns of chat consumption.
The real solution to this problem isn't to impose some kind of rule that people should stop spending an extra minute to be polite, but rather that we should all adopt conscious consumption patterns around chat, i.e. setting aside time each day when you focus strictly on work and ignore chats for x hours (your role permitting). Rather than letting the chat notifications dictate when you attend to them, you should dictate when you attend to chat notifications, and if it means breaking some important flow you have going the chat can probably wait.
Edit: I suppose the only exception to this is when the question is something that requires a one word answer and can be answered instantaneously, but if that's the case that's probably a sign you have larger communication problems in that things that are easily answerable are in the heads of workers and not stored in some uniformly accessible place.