Any smart business owner who can find a reputable and reliable outsourcing service that saves them both time and money would hire such services.
Naturally there has to be caveats to this. Homework needs to be done on the company. Positive relationships need to be built and they have to be able to perfectly understand not just your needs but your company culture and aims.
If you're able to free up time to provide better customer service/find new clients and save money in the process the question would be why wouldn't you do it?