Is It a Consequence of the EDE Protocols?

The EDE protocol is outstanding in terms of the number of nonsense that it needs and it keeps. If things start arriving out of order or the nonsense are all wrong, then you're probably under attack. So yeah, it's not easy to see why it was done that way. And I guess more other protocols settled for using something like a counter and maybe keeping track of the last counter value. That's like what the TLS record protocol does, essentially.