> My understanding of AGPL is that Amazon wouldn't even have to open source their service. So the license is not in the way of commercial exploitation.

There's no linking exception in the AGPL. As Google says, the risk is clear.

    "The primary risk presented by AGPL is that any product or service 
     that depends on AGPL-licensed code, or includes anything copied 
     or derived from AGPL-licensed code, may be subject to the virality 
     of the AGPL license. [1]"

IANAL, but some will go further and say that merely looking at AGPL code would be enough to trigger the license, since at some point you could "derive" things from the AGPL'd code base which could then taint every other closed source SaaS project you work on.

This could happen if you wrote an closed source alternative to the original AGPL'd project, and wondered how a particular algorithm was written, e.g.

[1] https://opensource.google/documentation/reference/using/agpl...