There are still great ideas dying in coffee shops. They're just dying on reddit too.
And _that_ is caused by a qualitative change - physical proximity has become way less important.
It used to be that you needed to convince Ugg, the big man of your tribe. Then you had to travel to Babylon -- or instead send clay tablets. Then you could be heard in Alexandria from Rome if papyrus copies of your words were transcribed and shipped. Eventually the printing press, telegraph and regular steam train schedules meant information about your speech in Paris could be news in Berlin in hours.
Today, in a few seconds, I put my hypothesis on the nature of the internet to a few hundred strangers scattered across the globe.
That's what I mean by a quantitative change. At each step, the number of people you could potentially reach has increased; the cost of doing so has fallen. I don't see it as a qualitative change, though, I see it as a series of smaller stepwise improvements.
An exaggerated comment, I think. There's a lot more content out there on the net, there's no way all content gets an equal share of attention - you end up with a lot of concentration and a greater amount of darkness. Actually every little thing you post and share is diluted in enormous mass of information. Even viral videos are usually obscure for several years before someone influential happens to find them and relink them.
It may have been true at the earliest stages of the web, but in 2012, it's pretty hard to stand out on the web and to benefit from the "giant magnifying glass" you mention.
The key is that the Internet enables a giant magnifying glass on everyone. This could have died out, but now it has a chance to live.