Both QA and accessibility tools have a common problem: They need full introspection of the user interface and need to simulate user input. The big difference is that QA tools need to simulate a real user, whereas accessibility tools need to give a user a different path to use a GUI. Mixing the two concepts just because it is convenient is not doing disabled people a favor. Developers might be forced to change the accessible representation of a widget to enable some QA tool to work, thus confusing disabled people with a bunch of unneeded functionality. Most GUI toolkits have hooks to introspect widgets, which is what should be used for QA.