Patents expire — typically 20 years after filing — and return to everyone. The problem was never a shortage of free ideas; it was the difficulty of finding them, understanding their current potential, and adapting them to a real problem.
The technical description work was already done decades ago. Adapting it costs a fraction of inventing from zero.
No royalty, no usage negotiation — the original protection has already expired worldwide.
Records from any country and era enter the same index, crossing different engineering traditions.
Old technical descriptions are ideal material for language models to suggest new combinations and uses.