I do actually wonder whether Dugtrio will harm stall more or offense more. Here's some popular offense/balance Pokes which I see as being reliably trapped or revenged by Choice Band or Life Orb Dugtrio......
Roserade--Against min Hp variants, Jolly LO Duggy has about a 2/3 shot to cleanly OHKO with Earthquake, CB is a guaranteed KO.
Mismagius--CB Night Slash is about 3/4 odds to OHKO. It can switch out, but Dugtrio does get Pursuit, which will almost certainly KO on a switch.
Registeel--Earthquake is an easy 2HKO, and Registeel's unboosted Ice Punch won't KO a healthy Dugtrio. Perhaps Duggy's arrival will finally give people more reason to use Steelix over Registeel, as Steelix takes less from Duggy's EQ and easily KOs back with Gyro Ball.
Blaziken--Even LO max SpA +nature Vacuum Wave only does 62% max to Duggy, so Blaziken's only hope to avoid being revenged is to run Choice Scarf.
Ambipom--Fake Out nearly OHKOs Dugtrio, but if Ambipom has already used that, CB Dugtrio's Earthquake has about 80% chance to KO with SR.
Moltres--Stone Edge obviously kills him, at least he can switch out though.
Rotom--Min Hp variants are facing an almost guaranteed KO from Night Slash after one SR switch-in, and like Mismagius, Pursuit can kill him if he tries to switch. Scarf variants are vulnerable to Sucker Punch, and Choice variants in general are gonna have to be really, really careful about using T-bolt.
Drapion--CB Earthquake is an easy KO on offensive versions, although bulkier variants can survive.
Espeon--CB Earthquake is a near guaranteed OHKO.
The prevalence of priority in UU prevents Dugtrio from being as scary as it might be, for example Hitmonlee and Arcanine both take tons from Earthquake but are unlikely to be revenged because they carry strong priority moves which will likely KO Dugtrio, but still. A metagame where Dugtrio usage is prevalent would really hinder the use of Blaziken, UU's trophy stallbreaker. Anyone who runs a wallbreaking variant of Blaziken would come up short against offense teams carrying Dugtrio, but without Blaziken, you lose one of the best weapons against stall. Meanwhile, stall teams only have one or two Pokemon vulnerable to being trapped by Dugtrio, and they can simply run Shed Shell if he's that big of a problem. Blaziken could run Shed Shell too I suppose, but he's not gonna be nearly as good at wallbreaking without his Life Orb.