Hi, obviously infinite loops will become an issue we will have to deal with as the service grows. Especially if we start running tasks at a much faster clip and not just every 15 minutes.
Caveats to the above are that you'd need to make sure that accounts in the channels are tied to single users (or join together the graphs of multiple users where they share channel accounts). You'd also need to handle odd edge cases with trigger fields and addins - such as a user @mentioning themselves and triggering an action to reply to the user who mentioned them.
I have to admit, I look at stuff like this and my first reaction is "hmm, what could possibly go wrong... could we somehow use this to calculate prime numbers perhaps?"