Actually, if you read http://www.paulgraham.com/startupideas.html and http://www.paulgraham.com/altair.html, this startup is the sort that pg was writing about. That's why I told these guys to include the bit about solving a problem they themselves had; it's a classic marker. See also http://www.paulgraham.com/organic.html: "Don't be discouraged if what you produce initially is something other people dismiss as a toy. In fact, that's a good sign."
It's a fun exercise to imagine a path from the small thing to a big thing. Can we do it in this case? I'd say so. Online distractions, addictions, and the exploitation of human attention by big-tech companies are a big deal. Reclaiming control over time and attention could be something that a lot of people care about.
My only other guess outside of the one listed is that it could be sold to Facebook or twitter after getting a large audience, because it aligns with historical acquisitions somewhat.
I'd be happy to be shown wrong in a year (I'd literally take anything over what I imagine is going to happen to it), but presently I'm mostly just confused.
Responding to the edits I only noticed after responding:
"Don't be discouraged if what you produce initially is something other people dismiss as a toy. In fact, that's a good sign."
I wasn't trying to discourage the people making the extension! I was mostly seeing if I could get any spare guesses as to what YC's mindset was when thinking about this.
Regarding whether what it's combating is a big deal:
Certainly, but I'm not sure if the solution to all of those is...a new big tech company, to put questions of profitability aside. It seems partially like bait to be acquired by a social media company, or Nielsen (which is a literal malware company at this point, they pay users to MITM their connections; a way to get the same data without paying seems like something they'd love).
The way YC looks for signal is different: simple and rooted in a few fundamentals. Do the founders seem effective? are they talking to users? and so on. The funny thing is, even though the fundamentals are simple and have been laid out in pg essays for a decade or more, it's surprisingly hard to reason with them. The mind doesn't like to stop with so little. I think that's why YC funding something like this feels paradoxical. (In the present case, it wasn't what they applied with but something they came up with later; but that helps make the point.)
"Bait to get acquired" would be considered a negative, since that's not how a business like YC ends up with the few big successes that make or break it. It's more like this: is there some plausible random world in which this thing ends up becoming a major breakthrough? It doesn't have to be probable, just fairly imaginable. And the founders have to seem like the kind of people who might, with luck, pull it off.
(Sorry for editing the carpet from under you! What I just wrote here was in response to your pre-edited comment too, but hopefully is still relevant.)
That last line in the second paragraph made it click for me, thank you! At first I was under the impression they were funded after the 6 MVPs, but it makes sense that they were funded before/during that! With that bit of context, "betting on the founders" in this case makes much more sense to me.
The extension looks cool (outside of it being proprietary) and it looks like you did a good job on it! I'm just trying to think of reasons as to why YC is trying to mimic Softbank. The only reason I can think of is that extensions occasionally get sold for thousands to malware vendors and the like, but that doesn't seem like something that would bring that much of a return, and seems too user-hostile to be something YC would bank on.