The reasoning is obvious, and "plausible deniability" is not enough to give Google charity. The more difficult you make it to block ads, the more impressions, and the more money made. Yet you believe people should be "charitable" to the same company that can't hire the manpower to defend their own users against bad faith DCMA takedown notices. Because they ran the analysis, and it wasn't worth the cost.
Best case scenario, Chromium loses market share, implements the parts removed from V2, Google likely kicks the can down the road to Manifest V4.
There's no reason to believe companies deserve charitability. Companies are systems designed to extract maximum value, and when the world around that system changes, the system adjusts itself. It's not the systems fault for trying to get more value, it's our fault for letting them.