The main problem is how to pass your conversation by script without for instance the use of gestuals which are usefull in order to express respect, complicity or even just a good laugh. That's why you must show details about your state of mind to your interlocutor. This is when smileys come in count.
But the Netiquette goes much further, for instance, it advises you not to say anything anywhere. Consequently postings ads in a newsgroup where it is in fact prohibited by the users can in the best case lead to a bunch of insulting emails; in the worst case... Nevertheless tolerance is general, and you really have to go very far to end up being rejected.
