So for you, it is more likely that the Gorosei received the scars prior to their immortality and at some point later in time were all bestowed with immortality and endless infinite regeneration that has to be removed with magic for them to be defeated, rather than sufficiently high and continuous attack power and sufficiently strong Haki, which is known for overcoming DF hax, being capable of permanently damaging them?
Is it really just "your headcanon vs. my headcanon"? I am sure one is more probable than the other just based on our knowledge on the mechanics of DF powers and Haki. Here we at least have some empirical values to work with (Haki overcoming hax, DF regeneration hax reaching its limit as evident with Marco), while your headcanon isn't based on anything. Them tanking a couple of attacks which are far from the peak attacks we witnessed so far, isn't proof their regeneration and immortality is special.
Is it really just "your headcanon vs. my headcanon"? I am sure one is more probable than the other just based on our knowledge on the mechanics of DF powers and Haki. Here we at least have some empirical values to work with (Haki overcoming hax, DF regeneration hax reaching its limit as evident with Marco), while your headcanon isn't based on anything. Them tanking a couple of attacks which are far from the peak attacks we witnessed so far, isn't proof their regeneration and immortality is special.