A65 exhaust cross over pipe

What’s the purpose of the cross over pipe on my 1971 Thunderbolt? BSA had it a few years before Norton, and I read that Norton did it primarily to quiet the exhaust for US regulations. I don’t remember loud pipes being much of an issue in 1971. The reason I ask is I had to destroy it to remove it from the headers, and wondered what would happen if I left it off and just capped the openings in the headers.

Triumph did it in 69 and used it to allow louder US silencers to be used in UK as they were made quieter, so it makes sense they used it on all the OIF bikes.