I think Mr. Kennedy is responding from a 20th century academic writerly tradition. In this statement I hear an echo of Auden's "Poetry makes nothing happen." Many 20th Century writers have taken this position, especially 20th Century American writers, and it is widely accepted.
It's even possible to trace the notion further back, to the Romantics, I suppose, and to the thinking of Shelly who felt that poets should be radicals but somehow ineffectual about it all. "Poets are the unacknowledged legislators of the world," he said, noisily abandoning the political lists to the Castlereighs of the world. Poetry, moving behind the scenes with its passions, moods and ideas, Shelly felt, would eventually carry the day.
Franz Kafka would seem to be the 20th Century poster child for this idea, the epitome of alienation and powerlessness, caught up in a faceless bureaucracy when he wasn't writing, he was eventually swallowed by the Nazi terror during world war II. Afterward, his influence emerged as part of the voice of existential alienation in the Mittleuropa of the time.
Yet on the whole, when we look at how Kennedy actually defines being an outsider — that is in terms of lack of instrumentality, lack of being able to order one's world, or achieve power in the greater world through force of will to order, and lack of ability to transform the world in this way — we have to question his premise. The name Geoffrey Chaucer jumps to mind from middle English Literature. In addition to one of out greatest poets, Chaucer was a major court administrator and a diplomat used to negotiate treaties between England and other countries. His patron, John of Gaunt, was the King's brother, and Chaucer didn't get to his position of influence by being ineffectual.
Should you consider Shakespeare himself, you'd have to notice that he not only was a pretty good writer, but that he was a shrewd businessman, made a large impact on his home-town by his purchases of property and involvement with civic affairs, but that he also navigated politically very troubled waters without getting in significant trouble with the government. His way of viewing the world did transform it, and not simply in his own era, but ever since. His ways of conceptualizing power may well be the basis of the way that western world has looked at power ever since. It is so pervasive that we don't even think of it as unusual until we compare it with non-western way of conceptualizing power. I suggest, for example, a look at Confucius in The Analects, with their heavy emphasis on ritual and rite. In one of the Analects, Confucius tells of how an emperor makes the kingdom quiet down by facing West. Of course, this had to be done properly, with the appropriate rites and rituals.
Other Eastern notions about power are well stated in the Tao te Ching.. Both these texts are interesting, but are used here chiefly as illustrations for how Shakespeare seems to have affected our theory and narrative on the subject so basically that we can't even see that it's been done.
Benjamin DIsraeli was not only a highly successful novelist, but also an English Prime Minister who alternated power with Gladstone for , I believe, decades.
And if you think about it, you can probably come up with your own examples, including that famous Irish Senator and Revolutionary, W. B. Yeats, and the Chilean Diplomat and Yeats' fellow Nobel laureate, Pablo Neruda.
As for myself, I can't balance my checkbook.
I'd guess, roughly, that there are as many effectual as ineffectual serious writers, or at least the scattering is pretty much as it is in the rest of the population. Now if you were to ask me about affective disorders, and drug or alcohol issues, I'd have to say that writers have more than their fair share. And heaven help the spouses of so many of us; they deserve canonization. That's my opinion.
Sincerely, Bob Kaven