Yes. When people talk about “turnkey” they are talking about higher level aggregate products though. For example, ZenDesk is a “turnkey” customer support product that is built on top of Twilio APIs. Dropbox is a “turnkey” file management product built on top of AWS S3 APIs.

These days, Twilio does have a lot more integrated solutions, but people still think of them as just the message transport layer that they started as.