Whether they promised to sell, or not sell, either way, they never promised equity.

Not promising equity if you never sell can be a sensible decision, because otherwise you create expectations of a cash-out that never comes.

Not promising equity if you do sell can be a sensible decision, because you keep more of the money to yourself. As long as you're transparant about not selling, employees can evaluate your remaining value proposition (salary, profit-sharing, perks) and decide whether it's worth it.

All 12k employees evaluated that value proposition and said it's worth it.

At some point the founders changed their mind. And that's okay, people change their minds. Unless they lied about it from the beginning and tricked people into a company vision they knew was bs, but the evidence doesn't clearly point to that.