Because Wizards has a major problem in this area, something that I've talked about before and has been widely known and discussed for years
You wipe the blockers that bother you, swing with everything else, and if lethal isn't quite there, feed the borrowed army to your sac outlets so nobody gets their creatures back
Seven mana for flashback is a ton, but it's good to have access to in a late-game pinch
But thats not the only reason this is significant
19, 2026 Can I activate a [Counter] effect and then activate another [Counter] effect
Now that prerelease events are done and dusted, and TMNT is out on store shelves, the most expensive cards in the set are making themselves known