Reddit IIRC was 6 employees until they were spun out of Conde Nast in 2011. (Some of those early employees are on HN; maybe they can correct me.)
PlentyOfFish was one guy until 2008, 5 years after its founding. It was doing a couple million in revenue then.
The big labor-intensive function seems to be enterprise sales. If you're just building a product for people to use or charging self-serve for use, you can do that with a small engineering team. As soon as you start charging $100K for the product or ad sales on the product, then you need to start hiring people to convince customers why they should spend $100K for your product. Of course, each salesperson makes more than they cost, so it's still rational to hire them.
There is almost no software priced between $1,000 and $50,000. Only big companies can afford to pay $50k+ for software and as a result they want a lot of hand-holding, support, and customization. Because they're spending so much they also want a lot of CYA assurances. Let's also be honest: they also want sales people to buy them lunches and send them bottles of scotch.
Selling to enterprises for $15,000 is a great way to go out of business: you won't be able to pay for enough staff to keep the sales pipeline flowing and you're too expensive for individuals and small businesses no matter how much value you deliver.
Yes they were also not charging their customer and thereby had no reason to offer customer support. These companies are more of the exception than the rule.
All this, as well as integrations: if a company is paying 100k for your software, they are going to expect it to integrate with their existing stuff in various ways and you've gotta support that, and a lot of times that involves hiring "integration engineers" to support that stuff while you (hopefully) build those things into a general purpose solution (which is more difficult than it sounds).
A lot of times enterprise sales folks are not particularly technical, so they'll often request support from a sales engineering organization.
Integrations aren't just enterprise things, as well.
Consider if you wanted to build a Spotify competitor. Disregarding the partner management/sales/distribution side of thing, but sticking solely to the tech:
You have to be able to ingest content from all your partners. If a new song is supposed to go live exactly at midnight on a given day, you gotta be able to deliver that. Not just media, but also systems for ingesting, reviewing, and publishing the metadata, album art, etc.
You have to run on a lot of devices. You need a desktop or web app, an iOS app, an Android app, a bunch of living room apps, Chromecast support...
You have to be able to bill people. I'd suggest offloading as much of this as possible so you're not touching credit cards yourself, but then it's still integration work. And now you have paying customers so you're going to be expected to have good reliability and responsiveness to issues, and to build tooling for your customer support team.
Paying customers and inventory - even digital inventory - make things turn into a lot more work quickly.
The "new" field in that file is YYYYMM data for when each employee started (though, looking through it right now, some of these definitely aren't correct, but they're reasonably close at least). Figuring out when people left is a little trickier, but estimates around a few significant dates:
That's only one way of measuring scale. They also burned something like $130MM the year before they were bought by Facebook.
If you're going to figure out how to monetize all those users in a profitable way, you're going to have to do more than just let them send text messages.
I'd be curious to know how many people work on WhatsApp at Facebook now, and whether they've become profitable on their own.
