I honestly don't agree as it still has dazzling gleam to hit dark types and the sheer power of either stored power or lumina crash is too much for every other pokemon. Also, it gets low kick which does a lot to gambit.
0- Atk Espathra Low Kick (100 BP) vs. 236 HP / 0 Def Kingambit: 148-176 (37 - 44%) -- 99.2% chance to 3HKO after Leftovers recovery
0- Atk Espathra Low Kick (100 BP) vs. 0 HP / 4 Def Kingambit: 148-176 (43.4 - 51.6%) -- 5.1% chance to 2HKO
Remember, this is 0 iv's and negative attack, and still at the very least 3HKO's.
I mean, you can't fit CM, Protect, Roost, Stored/Lumina, Dazzling Gleam, Substituteand Low Kick in a single set. Darks aren't even only checks to it:
Steels. Not Corviknight (unless Sdef vs no Roost), but Gholdengo (NP or Trick vs no Sub), Excadrill, Iron Treads, Scizor, Metagross, Jirachi and the already mentioned Gambit are good at checking Espathra.
Unaware Skeledirge with Shadow Ball.
Roar and Whirlwind, many Mons learn that now.
If no Protect or Sub Up, First Impression from Lokix, Slither Wing or Spidops.
Vs no Sub, Toxic or Thunder Wave/Glare ruin it.
Heart Swap Manaphy is fun and not only works vs Espathra.
Band Grassy Glide from Rillaboom is pretty close from a OHKO.
Offensive pressure in general. Espathra is not an immediate threat, you can send your Band Lando or Cinderace at least once.
Encore from something like Scream Tail.
Finally, while this is a Dark type, its a full stop to Espathra and has utility vs the rest of the Meta (especially if Gliscor ends up banned again) : Alolan Muk. Nothing Espathra has outside of Tera even remotely threatens Muk.
So, I do think there is enough counterplay to Espathra in a Tera less Meta, Mono Psychic typing is so terrible that only Mons with Arceus, Mewtwo or Deoxys Stats (+ the respective huge movepools) can be broken in OU with it.
This discussion is pretty irrelevant though, for now we fortunately live in a Tera meta and have other problems to speak about (fuck Deoxys and Gholdengo).