I'm not proposing anything "magically" happen. As a 25+ year dev I'm aware of the technical issues involved in aggregate storage. I also understand Nostr being designed for in-time events and not aggregates. If any solution would be unacceptable due to that design philosophy, then there's no purpose in having a reaction event, at least not for large public relays.

Once Nostr popularity has millions (or tens of millions) of daily active users requesting thousands or hundreds of thousands of kind 7 notes for each note being displayed, the load on the relays would be untenable. There's a discussion of possibilities on the issue I posted to the Nostr git if your'e interested in chiming in there.