Nah, they should just host it themselves. Bandwidth is much cheaper than AWS.
And don't forget the CPU throttling, noisy neighbors, IOPS and what not.
When things don't work, AWS doesn't tell you a reason why it didn't work. Instead they teach you lessons about how to architect your applications for failure by saying:
The EC2 team also recommend that you architect for failure using the white paper linked below:
https://d0.awsstatic.com/whitepapers/AWS_Cloud_Best_Practices.pdf
For people who use it as a VPS provider, they are going to be hard hit by other tenants who are applying the intended purpose.