Does " less established in the discourse" mean "not well accepted in spoken language?

[NewHopeR]

Context:

We are told that the active clause "I will always remember my first trip to Boston" sounds much better than the corresponding passive "My first visit to Boston will always be remembered by me." It sure does. But that's because a passive is always a stylistic train wreck when the subject refers to something newer and less established in the discourse than the agent (the noun phrase that follows "by").

[blackdragon]

to my humble knowledge and understanding. could i come up with my answer?
"Less established in the discourse..." could slightly be understood as "not generally known or used in spoken English"

[Barb_D]

No, not at all.

It means that so far in the conversation (in the discourse) we know more about the person or thing doing something (the agent) than we do about the thing that received the action (the subject in a passive sentence).

The passive is a "stylistic train wreck" almost every time you try to use a pronoun. To use a pronoun, you have to know who or what the pronoun is referring to (its antecedent). For you to know who or what the pronoun is referring to means that the antecedent has been "established in our discourse." You should not know more about the "who or what that is doing the action" than you should about the subject of the sentence if you want to use the passive.