I've posed this question as well several times to our Adobe rep and always got a "I wouldn't recommend it, but I don't see why you can't" type of response.
As mentioned, the only real issue here should be an impact on analytics.
Within Analytics for a single-app with a single account for each, you'd just see one folio that would contain all of the associated analytics data.
Within Analytics for a single-app with a single account for all, you'd see all of your folios contained within that account. If you're building lots of single-issue apps this would seem more managable to me, as you don't have a bunch of analytics suites to manage.
However, I'm not sure what analytics are tracked at the "app" level. For instance, if in SiteCatalyst, it tracks "app installs", then you'd get any app installs associated with that account, which would be problematic/false data if this login is actually linked to several different applications that share the report suite.
