For larger companies, there's a lot of "hidden" functions that you're probably not aware of as a customer. Just payment integrations in 100+ countries, with all the local regulations and reporting requirements is probably going to be rough to handle with a single team of 5 backenders. Then we have functions like marketing content management (every country has different copy and will probably want to be able to surface things slightly differently to maximize conversion), artist/podcast/audiobook tooling, the ad platform, hardware integration (for Spotify in your car/speaker etc), legal stuff (including GDPR and its equivalents), metrics & data analysis tools. And much more, and those are just some of the things you don't really see as an end-user.

I absolutely, 100%, agree that a small and focused team is the best way to get shit done, but for a large company the size of Spotify the amount of work is absolutely massive. I wouldn't be surprised at all if many teams at Spotify are small and tight-knit and doing great work at delivering kick-ass anti-fraud systems or moderation software to detect and report child porn etc.

Not to mention the obvious thing where the higher your revenue, the less percentual impact each employee needs to have to more than pay for themselves. While you might think it's ridiculous to have a full team dedicated solely to the main marketing page, that could be extremely worth it if that team increases conversion by 10%, as an example.