Labelling the user interaction nodes that you've described with the WebUser classification is the intended purpose of this classification and probably best practice, however I would not say it is strictly required.
The WebUser node type classification is in most cases probably used specifically to avoid assigning agents and listeners to the nodes that are supporting user interaction so when you read that agent documentation from the perspective of the nodes rather than an agent it could be a little confusing since there are probably rare use cases for a WebUser agent.
For example, on my project we are using the WebUser classification on all the user interaction nodes but they have no agents or listeners running on them except the bare minimum RunOnAllNodes system agents.
@jespinozasokal Thanks for your response. In that case do we need to assign any node type (not even WebUser) at all if it's just a user/non-user interaction node (if there are no Agent of WebUser Type)?
As per the below article - "If you do not assign a node type to a node, Pega Platform, by default, associates the node with four Pega-provided node types: "BackgroundProcessing,Search,Stream,WebUser"