

I mean, this is essentially all hiring processes.
The way to get actually good employees is to be the sort of place that actual good employees want to work for. Good pay, good work-life balance, good managers and company culture, work that is enjoyable and meaningful. Then, you hire through social networks. The founders start off as people who meet through informal social networks. They hire their friends. And then they ask their friends for further recommendations. The best way to know if someone is a good hire is if you have actually worked with them before. And at this point, the interview is really just hanging out, shaking hands, and having lunch before you sign some paperwork.
I mean, kind of. I wouldnt say extroverts, so much as “people with good/decent social skills”. Introversion/extroversion is a sliding scale, not a dichotomy, and it refers more to your propensity to gain or lose energy from social interactions - not your ability to socialize.
While many more introverted people find socializing more difficult in general, there is no reason why they can’t develop the skill.