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.
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.
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