That is the real treasure being lost.
It's what happened in software with H1Bs and off-shoring, and earlier with the off-shoring of the American shoe-making and garment industries: companies made short-term profits by exporting the common techniques and "tribal knowledge" that American workers had accumulated among ourselves, but which weren't really the proprietary trade secrets of any one company.
Over time, the people in the countries we exported the knowledge to, developed their own companies in competition with the American companies whose knowledge they now had. But by that point, the CEOs who ordered the knowledge transmission had moved on to other industries to wreck.