ARV is leaving out a bunch of context to the discussion. The debate started in regards to whether or not the Yonko were superior to the Marines. Someone said the Marines needed to form the Shichibukai to make up the difference. I said the Marines were equal to the Yonko, and the Shichibukai were created to be equal to both, hence why they're regarded as three separate entities, the THREE Great Powers, rather than a different label for the Shichibukai and Marines to be one entity. If it was Shichibukai+Marines=Yonko, there'd be no reason to have them be two separate entities.
As that discussion continued, someone(can't remember who, possibly him) asked me how could the Shichibukai possibly equal the Yonko, and I mentioned that quite a few of them had kingdoms under their belt, crews, and connections/allies. In that same discussion, I admitted that, in practice and especially with the current iteration, the Shichibukai are falling short, but that's on purpose. They've been portrayed as a failing system, with them falling short in aiding the Marines in the word, many of them losing or abusing their positions, and it being a plot point via Fujitora that there are those who want the system to be disbanded.
The point of me saying that is that the conception of the Shichibukai isn't proof that Marines are weaker than Yonko, as they were conceived to be equal to both, even though they're probably failing to do that in practice.
