Investment banks recruit bright young graduates, putting them through a tough selection process (c.f. all those hard-working interns we keep reading about), and select the ones who perform/conform the best. The rationale for bringing in young (as opposed to experienced) people is that they'll work their asses off, can be moulded to fit the culture (i.e. independent thinkers aren't necessarily sought), and (perhaps most importantly) are too junior to present a threat to the incumbents.
If Google's going down the same path, it may be a sign that their corporate culture is solidifying, which would be a bad sign, IMHO.
For the top elite of experienced engineers that may not be the case, as they will come with some overall good analytical skills that Google wants. But for most in our industry, what we have learned over the years is how to be good in various sets of tech around our platforms of choice... and that is mostly irrelevant to Google, as they have their own platforms.