The real power is in its ability, which can make a spell uncounterable
The Swarmweaver There are more explosive or more consistent insect token generators than The Swarmweaver, and there are more impactful lords and payoffs that dont need you to enable delirium
Cascade Spells Ardent Plea Bituminous Blast Bloodbraid Elf Captured Sunlight Demonic Dread Deny Reality Enigma Sphinx Enlisted Wurm Kathari Remnant Maelstrom Nexus Stormcaller's Boon Violent Outburst Besides Bloodbraid Elf being the end-all of Standard for a season, people haven't done very much with Cascade besides finding cards from the Ancestral Vision cycle
On the higher end, you can play a pretty mean control game with lots of bonus Blood value, lifegain, and removal spells like Bleed Dry and Grisly Ritual
and while still on the battlefield, Phantasmal Image was a Messenger without counters
It's wild that Darksteel Ingot went from staple to basically unplayable, but that's what you get when your format is ripe for monetization