can sub personalization lead to 20x reply increase?

I found a 2024 paper on cold email personalisation.

Personalised emails: 62-70% open, 8.9-17.4% reply. Same email with the personalisation fields removed: 17% open, 0.4% reply.

That is roughly 20x on replies. The open rate collapsed as well, which means the subject lines were not held constant as well.

Is it any way logical to assume open increase (via just subject personalization) can lead to reply increase without body personalization? Has anyone actually tested it?