I don't get what you're arguing here. Sonak pretty much just paraphrased your post. And your post was about Kim's screen time, not Kes's supposedly diminishing role.
Screen time-the amount of time you physically see the character on the TV screen per episode per season
Not to be confused with character development or the amount of episodes a character is featured in each season. Screen time isn't limited to the amount of eps. that character is featured in but rather how many times does the audience physically see that character on their TV within in each episode.
For example: Harry is in the entire two parter of "Future's End", Kes has two small scenes. You see Harry in "Macrocosm" Kes isn't in it all. I don't think she's in "The Chute", "Remember" or "The Q and he Grey" either but all the rest of the cast is.
And I still don't get what you're arguing. I don't think there's been any disagreement about the definitions of "screen time" and "character development."
Other posters have written fairly thorough posts about the amount of focus Kes got throughout seasons 2 and 3. For a secondary character, she has one of the more substantial roles.
The number of lines and the amount of screen time she got is less important to me than the impression she left. I have a good idea of who this character is, I could give a detailed description of her personality, and she captured my imagination to point of making me wonder about the parts of her life we didn't see. This is a lot more than I can say for most of the other secondary characters.