I am requestion this feature because it's extremely valuable to be able to have certain flags turned on and off depending upon a value change. Below is the reply that currently, only leads and contacts are able to be edited.
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Thank you for contacting Marketo Customer Support. My name is Michael and I am happy to help you.
By design Marketo only edits lead and contact objects, not account objects. Here is a community article detailing this design:
https://community.marketo.com/MarketoArticle?id=kA050000000KzbQCAS