Ask HN: Why is Toptal so successful?

They appear to be a fairly normal contracting company- they receive contracts for work for x number of dollars per hour, and they pay contractors y dollars. There are literally millions of companies on Earth that do this exact thing- lots of consultancies, agencies, there are staffing agencies who may be specialized in a particular kind of tech, etc. The industry has an incredibly low barrier to entry.

What specifically is it about Toptal that made them become such a successful consultancy? Is there any kind of secret sauce that distinguishes them from other 'we provide contractors at y rate' companies? If you're in a management role at a tech company you are absolutely inundated with pitches from these firms. Is it just an execution thing on Toptal's end- some % of an industry will do the basics much better than the rest?