So I've been watching a couple of the top speedruns in the Coop category, and I've noticed that sometimes they use a Mythril Anvil to craft Hallowed Armor for the late game bosses. However, they never even spawn Mythril in the world (by destroying an altar)

The only way (as far as I know) to get a Mythril Anvil without spawning it, is by fishing, but this would require at least 2 Mythril Crates or better, and definetly does not seem like it's possible to do within the sort time the non-host aren't helping with bosses or anything.

So I guess my question is; do people just bring a Mythril Anvil into speedruns via the coop person? Or does anyone have an explanation?