This comes as Micronesian leaders this week announced their intention to withdraw their five countries from the premier regional body, after their candidate wasn't selected for the organisation's top job.
The presidents of Nauru, the Federated States of Micronesia, Kiribati, Marshall Islands and Palau said that South Pacific countries dishonoured a "gentleman's agreement" to rotate the post evenly among sub-regions, and that it was Micronesia's turn.
When leaders of Forum countries were unable to reach consensus over the appointment over who to appoint as Secretary-General at last week's online summit, the matter went to a vote.
The vote was by secret ballot, which went the way of the former Cook Islands prime minister Henry Puna who pipped the Marshall Islands diplomat Gerald Zackios by 9 votes to 8.
"The normal practice is that the role of Secretary-General is by rotation with the three regions of the Pacific, that is Melanesia, Micronesia and Polynesia," said O'Neill, a veteran of numerous Forum leaders summits.
"Leaders who are new to that tradition need to learn to appreciate and respect this for the sake of solidarity and unity within the Pacific."
However, it's not the first time that the Forum top job was decided by a vote: in 2002 the Australian Greg Urwin was appointed after the matter was put to a vote. The sub-regional rotation theory was not applied then either.
But O'Neill said that taking votes was never something that was encouraged at the Forum Leaders level.
"We always want to reach consensus decisions the Pacific way through compromise," he said.
At least one Micronesian leader accused New Zealand and Australia of failure to compromise at the Forum.
Palau's President president Surangel Whipps Jr claimed that combined with Polynesian countries, including those in New Zealand's realm, South Pacific members had an unfair dominance in the Forum through sheer numbers in the decision-making process.
But New Zealand's prime minister, Jacinda Ardern, rejected claims that her government backed a particular candidate for the secretary general's position.
"It's just not true, we were looking for a consesus candidate. If anything, we have often been very aware of our role in the Pacific Island Forum, often standing back in some of the debate discussions, trying to be really supportive of that consensus approach, making sure."
Yet Whipps argued the consensus failure at the Forum highlighted the need to review its composition.
"For example, we have other islands in the north Pacific, we gave Guam, we have Saipan, we have Hawaii, we have American Samoa. Why aren't they members of the Pacific Islands Forum?" Whipps said.
Samoa's Prime Minister Tuilaepa Sailele Malielegaoi appears to have been listening. He is promoting a pan-Samoan voting block for the Forum.
American Samoa currently only has observer status and cannot vote, but Tuilaepa said he saw great benefit in the US territory becoming a full member of the Forum.
He said he was optimistic American Samoa was only half a step away from joining the Forum, considering they were already an official member of the Polynesian Leaders Group.
While Whipps suggested the composition of the Pacific Islands Forum should be tweaked, O'Neill didn't see much benefit in removing Australia or New Zealand.
"Australia and New Zealand are still part of the Pacific community and as developed nations, they need to play a more active role guiding the delivery of social and economy development programs within the region," he said.
Meanwhile, the erosion in consensus-building was not lost on Niue's premier Dalton Tagelagi who expressed sadness at Micronesia's decision to leave the Pacific Forum.
He described it as unfortunate that Forum leaders were not able to meet in person due to Covid-19, hoping that in time the problem could be resolved with dialogue.
It will take a year for Kiribati, Marshall Islands, Federated States of Micronesia, Nauru, Palau to complete secession formalities. The door is not entirely closed yet.
Tagelagi acknowledged countries were free to make their own choices but said "we are strongest when we are together".
Photo RNZ Pacific Caption: Papua New Guinea's former Prime Minister Peter O'Neill