Early interoperability standards in HC were onerous and heavy but also necessary. HL7 V2 came to maturity in the 90s. It was 80% standard and 20% a framework. V2 lacked a consistent data model and had many more challenges but represented the complex world of healthcare. Interoperability was a science project.
HL7 V3 came along at the turn of the century to address the v2 challenges but did not provide backward compatibility. V3 presented itself as more of a standard than a framework for negotiation.