When I had it disabled, iMessage would turn on with every major update. This prevented me from receiving SMS from iMessage users when I would turn it back off.

Now that I am using iMessage, I can't view past media or use the search functionality (for either messages or contacts). I actually thought this was by design until someone told me otherwise.

The very worst thing was that I have two people in my life who harass me. Blocking them would mean I can't keep a copy of threats I receive, so I kept them unblocked with read receipts disabled. With the iOS 26 update, despite having read receipts disabled (for these chats and in the global setting), they apparently received read receipts from me.

This should never happen. It gives the impression that something is thoroughly dysfunctional within Apple.

Not sure what parent was referring to, but for me iMessage frequently gets confused when dealing with devices that don't have a phone number or when moving SIMs between phones. Sometimes messages silently get routed to other devices or seem to disappear into the void in these cases which can be extremely frustrating. Since it's Apple, there's no way to tell when this is happening and try to correct it either. In theory iMessages tells me I'm sending a message to John Smith, but am I sending it to [email protected] or 555-122-4455 or some other alias associated with that Apple user? No way to tell until you get some error in iMessage that the message could not be delivered and no way to explicitly select which alias is going to receive it as far as I can tell.

Edit: Admittedly, I have a poor mental model of what is even happening in these cases. Are these "aliases" or something else? Unfortunately, Apple doesn't help elucidate the problems/mechanisms here. The only insights I have into what's happening is from mysterious errors and failure to deliver messages.