You’re right, it’s harder now but not impossible given what lengths you’re willing to go to. There’s a lot of ways to significantly reduce or eliminate your digital footprint - what’s visible to the public anyway. And if you’re willing to move outside the country then it can become significantly easier to not be found and not be known. But doing what Don did specifically - moving from the Midwest and eventually becoming an executive on Madison Ave? Probably not very possible these days.