IRL relationships still involve a lot of imagination. We can't directly experience other people, we have to rely on our fallible and low bandwidth senses.

Real life is orders of magnitude more bandwidth than anything online. Online allows a lot more/easier maladaptive disconnection.

But yes, many (most?) in person relationships are also ‘imagination’ driven. Some very pathologically so (NPD, BPD, DID, etc.).

No I don't think so because the other person had this too. It's a more direct connection between minds, with no distraction of physical attributes. I can physically like the appearance of another person or dislike it, and it really affects my behaviour. Because this I'm not really being open and honest because it will introduce other factors that have nothing to do with what we are talking about. For example if the person is a beautiful lady I will be very inclined to impress her and this will affect everything I say and make me really shy. In a chat environment this is not a factor. That part doesn't exist, I'm just communicating with their mind.

Also, I don't really imagine the other person if all I have is a nickname. They remain just that, an entity. I don't imagine their physical appearance at all. They don't have a face or even a gender until I know it or is obvious from the nick. All I have is the things they say, the beliefs they have. It is more pure than their physical appearance which in many cases they don't control. Is that so weird?

I know not everyone has this ability but I do and I notice it a lot. Also, in many cases it does work out in real life. Just sometimes it doesn't.

It's pretty weird because of how maladaptive it is, practically?

On the other end could just be a really good chat bot. It may feel good at the time, but what future does it hold, and/or what useful feedback are you getting from it that isn't just a mirror of yourself or someone similarly disconnected physically?

Dissociative Identity Disorder is a problem for a reason. At the end of the day, real life/our physical selves do matter.