Technology was very much a part of the design language used for the Iron Horde
The entire point was that the Iron Horde war machine was built around the use of technology, instead of demonic magic, this conception of yours that the only ones designing, building and operating said technology were the remnants of the Blackfuse Company who managed to get to Alternate Draenor has absolutely no basis and seems to just be a product of your own bias, here are multiple orcs who designed, built or operated various technological aspects of the Iron Horde
https://wow.gamepedia.com/Solog_Roark an "engineering prodigy" who designed the Iron Docks & Dreadnought ships
https://wow.gamepedia.com/Operator_Thogar who oversaw the the Grimrail train system
https://wow.gamepedia.com/Machinist_B%27randt A "machinist" who was overseeing the Iron Horde "super weapon" during the battle of Shattrath
https://wow.gamepedia.com/Master_Siegesmith_Uratok a "master siegesmith" who was assiting the Thunderlord clan
There are only like 4 named Goblins who play any role in the iron Horde war machine every other Goblin we see are nameless technicians & engineers of which we also see an equal number of Mag'har technicians & engineers among the Iron Horde
Even then the idea that a race can only have a class if they personally invented the concept/techniques has absolutely no basis, Humans taught Dwarves about the Light giving them Priests and Paladins, Night Elves taught the Tauren how to be Druids, Pandaren taught everyone else how to be Monks.
We still see the Mag'har utilizing said technology 30 years later in their war with the Lightbound, numerous siege machines and iron stars, we also literally only see a single war camp which was managed by a Warsong & a Frostwolf who were hardly the technologically inclined clans anyway, they were also a peace for decades so the massive technological war machine they built probably wasn't needed. we also see the Mag'har using Iron Stars in the faction assaults.
Heritage Armor is meaningless here, does the Kul Tiran heritage armor "fit" a Shaman or Druid or Death Knight? does the Goblin or Gnome fit any class thats currently in the game? does the Dwarf heritage armor fit a Mage, Monk, Warlock, Shaman or Priest?
Nobody is suggesting a Tinker/technology class be as widespread in terms of distribution among races as Warriors, Hunters or Rogues, most suggestions put have them being limited to races who have shown an inclination or willingness to use Technology in some form as a greater part of their society
Dwarves and Dark Irons (Golems and Mole Machines)
Orcs and Mag'har (Iron Horde & Adapted Goblin tech)
Goblins (no elaboration needed)
Gnomes and Mechagnomes (no elaboration needed)
Draenei and Lightforged (Warframes & argunite/arkanite powered technology)
Blood Elves and Nightborne (Arcane powered Constructs)
6 Alliance races and 5 Horde races, 11 races which puts them on a similar level of distribution as Shamans & Warlocks.