Ovinomancer
No flips for you!
Jeremy Crawford has already directly stated that attacks are not simultaneous. Please read the thread.
Furthermore, instantaneous spells can't be dispelled because the rules specifically say that they can't be. Your silly extrapolations aside, what you're saying is complete nonsense. You're blinding yourself from what the rules say in favor of your invented claim. Anyway, the above quote from JC clearly shows that:
1. You don't pick all targets at the same time
2. Multi attack spells are done in sequence, one attack after the other.
3. Attacks like these are not simultaneous.
This pretty much removes any possible doubt that what you're saying isn't factual no matter how much you want it to be or you think your personal definition of a word is more important than the definition used in the edition itself. Stop trying to spread misinformation.
So you're in agreement with me and Arial that a readied action can occur between blasts. Excellent, progress! I'd be interested in see what you have to say about Ariel's contention that you could use dispel magic as a readied action to chop off the remaining bolts.