Take it when you want to lean into a massed Boyz swarm and can field multiple large mobs. It's the thematic infantry-flood build, strongest when your list is genuinely Boyz-heavy so the invuln, resurrection and full-mob thresholds all come online. It's weaker with elite or vehicle mixes, since only Boyz benefit from the rule. At 3 DP it's priced alongside War Horde and takes your whole budget at 2,000 points, so unlike a 2-DP core it can't be topped up with a 1-DP support like More Dakka!. Everything the list does has to come out of Green Tide's own rule, stratagems and enhancements.
Sample gameplan: flood the board with 20-strong mobs, a character carrying Raucous Warcaller to lock a unit at the 5+ invuln, and Braggin' Rights to keep paired units at full-mob status. Advance up under the invuln, using Go Get 'Em! to reposition when shot and Come On Ladz! each Command phase to rebuild casualties. Call the Waaagh! as the horde reaches the enemy: with Tide of Muscle guaranteeing charges and Competitive Streak re-rolling all Wounds, a full mob buffed by Ferocious Show Off (+3 Strength) plus the Waaagh! delivers an overwhelming number of high-Strength attacks.