its not about BM being unable to end Marco quickly.
I expected this. I rate Marco very high.
or in better words, I rate top tiers closer to YC then most would.
its the fact that BM had no way of knowing that her homies could fall to Marcos flames.
she would use them like vs any other foe.
i.e. not trying to keep them out of harms way as its not necessary. canon material said they are borderline invincible (too bad BM gets matched vs any ability that can magically harm them...).
this is not something you can hold against her or give Marco credit for.
compare it to WBs gura countering Kuzans freezing.
no one, Kuzan included, imagined that the gura could do this.
if the gura could not conveniently do that then Kuzan would have 1 shot WB.