[Ryan]

Running a service as sprawling and complex as Twitter is a huge task and takes a LOT of people. There's far more to the service than just tweets.

You've got your platform teams building all the underlying infrastructure. Twitter predates the cloud—literally, Twitter launched one week before AWS—and runs almost everything in its own data centers. There are teams running various internal storage and messaging systems, some of which had to be custom-built because nothing else could handle their scale back then. Twitter operates some of the largest Hadoop clusters in the world, that requires a lot of manpower to keep running.

You've got the teams in charge of the consumer experience. Twitter.com, the mobile apps, etc. There's a team maintaining notifications, another maintaining DMs, yet another in charge of the home timeline. Add to that product managers, user experience researchers, data scientists, internationalization teams and far, far more.

Then you've got the revenue side of the company. Building an ad network this size is, again, non-trivial. There's a team maintaining payments infrastructure, another building the internal tooling to manage ads, another building sales tools to sell the ads. And then of course the sales team itself, which is sprawling and worldwide.

Twitter handles a lot of data. That in turn requires a lot of privacy engineers and security specialists to keep it safe.

My last big project was an external-facing API to let developer customers hydrate the status of billions of tweets in a matter of minutes to determine which ones they needed to delete from their own storage. I led five other engineers on that project. Now imagine how many other unseen features the company needs to build and how many five-person teams you're going to need to get there.

Just the API platform required over 100 engineers, another dozen product managers, 100+ sales people and so on.

You need a small army of lawyers given the constant legal battles the company faces around the world. How many accountants and business analysts do you think it takes to operate in 100+ countries?

Companies like Zoom and Whatsapp are poor comparisons given the product differences. Those are one-to-one or one-to-few and they're not multi-sided marketplaces. Zoom's product surface is minuscule compared to a social network. Twitter is realtime many-to-many messaging with an ad market bolted on top.