Are artists really as powerful as Arthur O'Shaughnessy makes them seem in his poem Ode?

I’ve quoted the poem at the bottom. He talks of artists raising and trampling empires. Do artists really have that much power? I know that some artists are also protesters, but are they really made that much more powerful as protesters, simply because of their talent and/or popularity? What would make artists especially important in political matters? What are some examples of artists having such profound effect on empires? Is this strictly a historical phenomenon, or could it (does it) still happen today?

Here’s the poem: Ode, by Arthur O’Shaughnessy

We are the music-makers,
And we are the dreamers of dreams,
Wandering by lone sea-breakers
And sitting by desolate streams;
World losers and world forsakers,
On whom the pale moon gleams:
Yet we are the movers and shakers
Of the world for ever, it seems.

With wonderful deathless ditties
We build up the world’s great cities.
And out of a fabulous story
We fashion an empire’s glory:
One man with a dream, at pleasure,
Shall go forth and conquer a crown;
And three with a new song’s measure
Can trample an empire down.

We, in the ages lying
In the buried past of the earth,
Built Nineveh with our sighing,
And Babel itself with our mirth;
And o’erthrew them with prophesying
To the old of the new world’s worth;
For each age is a dream that is dying,
Or one that is coming to birth.