Writing v talking
Internet, by forcing us to write rather than talk, has changed our perception of the others quite a lot!
When you're talking to someone next to you, more than 60% of what you communicate is non verbal (eye, face, body movements) and it reaveals a lot more than what you talk about. Another advantage is that it's a lot easier to correct the other or yourself (happens instantaneously).
If you write, the other might not perceive what your state of mind was, can only rely on what was written.
A danger is that once the post is sent, there is no way it can be corrected and it's very difficult to come back to it.
This is why so many hide behind pseudos..or those who don't , are very careful with what they write about.