Ask HN: Do you skip phone interviews for Google/FB/Tier-1 company engineers?

I am assuming that phone screens/interviews are primarily to weed out obviously bad/not a good fit engineers. Also, I have heard that most startups/companies would skip phone interviews for an engineer from a Tier-1 company because they are likely to do well at an onsite interview (They are essentially pre-vetted by their previous company is the reason I have heard from hiring managers).

Are there caveats to this? Only skip phone interviews for engineers above a certain level? Phone interviews are primarily used for selling the candidate on the company/opportunity/role and not as much of a technical "interview"?