You can't reason like that. The market value is simply the price the customer is willing to bear. If Microsoft can bear an $60k per year increase to hold onto these engineers, then that's their "true" market value. In other words, they're getting paid exactly market value right now, and they were getting horribly underpaid before.
Side note: This misconception about "true market value" is probably the number one reason as to why engineers are underpaid. If the person on the other side isn't challenging your price, you're lowballing yourself.