In the beginning it was never about Shanks and Mihawk. Zoro fans used "Mihawk>Shanks" as a means to push "Zoro>Luffy" agenda, so Luffy fans started coming up with ways to counteract Mihawk>Shanks. Eventually Shanks and Mihawk got their own fandoms, but the damage was already done, and the rest is history. I know this, because I'm the one who came up with a lot of the counterarguments in favor of Shanks, and I was never even a Shanks fan. Back in those days, the debates seriously were never about Shanks and Mihawk though.