Everyone knows SPI likely has BS numbers made from very creative accounting. I wouldn't doubt that, that's the case with many of them. I'd be interested to know how much they actually make. I think that this type of thing - going beyond superficial aggregation or testing - would keep your traffic there.

Anyway Nathan Barry, the founder of an email marketing company Convert Kit - a company on your list, says it pretty well: the best way to drive traffic to your products is to first drive traffic to yourself.

https://vimeo.com/95680313 - A talk by Nathan Barry (Check out that Vimeo account for more talks from founders)

Driving traffic to yourself is typically done with content marketing. Here's a podcast from Empire Flippers - a company on your list - interviewing the founder of another company on the list, WP Curve. https://empireflippers.com/wpcurve/ (Note that podcasting and blogging is Empire Flippers' form of content marketing, and a big reason why they're as big as they are)

And here's an in depth guide by Neil Patel https://www.quicksprout.com/the-advanced-guide-to-content-ma... (Quicksprout, which seems to be an umbrella company for niche sites, also looks like it has transparent revenue btw)

In closing, I'll reiterate that it's probably most important that, like Y Combinator itself says, you build something that people want.

You can shoot me an email if you want. I'm a willing wall to bounce ideas off of. ryanacalvo /at/ gmail