800 hires a year means ~15 people starting every week. Every one of those 800 positions likely received hundreds of resumes, which needed to be sifted through. Then you need to have calls with each candidate, narrow down the pool further. Then all the onsite rounds. For an initial team of 200 that is an impossible task.
To hire so many you have to hire a lot in parallel. Also, even once hired, probably the engineer shouldn't have "interview more engineers" as his first priority.
I don't think many people on this board comprehend that there exist professionals at most companies whose sole responsibility is to identify, recruit, and onboard new employees.
Or that most companies are willing to hire people who aren't perfect candidates because a fair amount of internal training is expected. Hiring only unicorn candidates who already have the perfect qualifications and don't need any training/onboarding is a peculiarly Silicon Valley phenomenon.
