whereas a thousand hobgoblins is a walk in the park with Pathfinder (1) and older editions of D&D. That means more mobs stay somewhat relevant and that you may face those epic monsters while still not high level yourself. .
You really need to let me talk to your GM about the proper use of hobgoblins in PF. They are nasty in cave environments for low-to-mid-level parties.
In the Classic "Red Hand of Doom" 3.5 module your main adversaries are the Red Hand army, and they are hobgoblins and bugbears with PC classes and it´s an advanced difficulty module, even the in the PF version.
Take a look at the CR of the hobgoblin enemies of the campaign. No way you beat thousands of those, not even dozens. The standard encounter is 3 +/- 2 creatures for a 4-player-party.
Red Hand Regular (Fighter 2) CR 1
Red Hand Veteran (Fighter-Phalanx Soldier 4) CR 3
Red Hand Sergeant (Fighter-Tactician 5) CR 4
Red Hand Bladebearer (Fighter-5 with PC wealth) CR 5
Red Hand Cleric (Cleric 5) CR 4
Red Hand Warpriest (Cleric 9) CR 8
Red Hand Warmage{War Adept} (Sorcerer-Draconic Bloodline 7) CR 6
Red Hand Warchanter {Mindbender} (Bard-Savage Skald 9) CR 8
Red Hand Avenger {Doom Fist Monk} (Anti-Paladin 6) CR 5
Goblin Worg Rider (Goblin Fighter-Dragoon 4) CR 3
Blood Ghost Berserker (Bugbear Barbarian 4) CR 6
Red Hand Brute (Ogre Barbarian 2) CR 5
¿Maybe you've mistaken the videogames based in D&D and PF for the Tabletop? If that´s the case I do not think you can compare a videogame based on previous versions of D&D and Pathfinder with a session of the D&D 5e Tabletop.
It would be like saying that Hamilton and Schumacher are not such a good pilots because when you play "F1 racer" with them you made it 20s faster per lap in the videogame.
