Linux is notoriously fragmented/duplicative, and an OS isn't the solution to anyone's actual business problem. A well-factored solution to a specific problem would be much smaller, compare e.g. QNX.
> Facebook is probably more lines of code.
IIRC Facebook is the last non-monorepo holdout among the giants, they genuinely split up their codebase and have parts that operate independently.
Does Facebook have more than 5M lines of code now? I'm sure they do. Does that actually result in a better product than when it was less than 5M lines of code? Ehhhh. Certainly if we're talking about where the revenue is being generated, as the article wants to, then I suspect at least 80% of it is generated by the <5M that were written first.
So I mean yeah, on some level solving the business problem can take as many lines as you want it to, because it's always possible to add some special case enhancement for some edge case that takes more lines. But if you just keep growing the codebase until it's unprofitable then that's not actually particularly valuable code and it's not very nice to work on either.