One of the most frequent questions asked of people proposing various Utopian schemes designed to "improve the world" is usually preceded by "I completely agree with your proposed solution to humanity's problems..."
The questioners display impatience with the enormity of the task of achieving some lofty goal like World Peace or Universal Health Care or a Basic Income Guarantee (my current favorite). The most frequent response is to "keep on keeping on" and hope/expect Dr. Time to be an ally.
Because I've reached "dotage" it's clear that, at the very most we are vectors pointing to said aspirations - the idea of a "turning point" or some historically vital landmark (usually a pariah) is pretty vain. Tim's book is almost self-deprecating in a field replete with "fathers of the Web Age" who claim primacy, be they Ted Nelson or Doug Engelbart or Gates/Wozniak and now Wales.
Each took part but so did we all either leading, following or staying pretty much out of the way.
But how about Ghandi or Dr. King or perhaps Jackie Robinson? Weren't they true differnce-makers? Yes, in a way and they had certain aspects in common that may lead to an answer to the Sermon's theme: although they talked extensively, they also walked with a certain affrontery towards the institutions they sought to change. Trouble is they all died before their goals really were attained.
So, I guess that in general the answer is, as usual, to think globally and act locally, i.e. seize command of what you can reach. You too can be the mayor of Podunk and maybe shake so much that the ensuing rain of shed water will float us towards "The Promised Land"! Worth a try.