Yes, what the OP is saying is related to one of the paradoxes of security/defence, i.e. the fact that the more one increases its defences (like Google is doing) then the more said increase of defences also pushes one's adversary to increase its offence capabilities. Which is to say that Google playing it safer and safer actually causes their potential adversaries to become stronger and stronger.

You can see those paradoxes at play throughout the corporate world and especially when it comes to actual combat/war (to which actual combat/war these DOSes might actually be connected). For example the fact that Israel was relatively successful in implementing its Iron Dome shield only incentivised their adversaries to get hold of even more rockets, so that the sheer number of rockets alone would be able to overwhelm said Iron Dome. That's how Hamas got to firing ~4,000 rockets in one single day recently, that number was out of their league several years ago when Iron Dome was not yet functional.