Let's not blame engineers for what is effectively a political issue. If ads are an issue, let's get the law to handle it.
If you think something is wrong, the first step is to not do it. If you think it's so wrong it should be illegal, you can take the optional second step of trying to change the law.
There are some circumstances where you think something is wrong, but not doing it would be impossible or require really drastic life changes. For example, maybe you think driving a gas-powered car is wrong because it contributes to climate change, but you can't afford to buy an electric car or move somewhere that doesn't require a car. This is not one of those cases. The author has 10 years of experience at Google and could easily find a very well paying job either at another department inside Google, or at another company.
My point is that quitting or getting a different job accomplishes nothing. With a multinational corporation like Google, they will never struggle to fill roles. If you work in these positions, you at least have influence on product growth, and you can use the massive amount of money earned to lobby against harmful behavior. If you quit, you have no internal influence and have less money to take political action with, meaning the only way you could change things is through legislation.
The way I look at it is like so:
I think most people want to bring a net positive value to society. One way of doing that is working on something whose intrinsic value to society is neutral or nebulous (or just not thinking about it too hard), and compensating for that giving the money we make to other organizations that are definitely contributing positively. While this is better than not doing so, I think it misses out on the leverage that exists in what we build vs. the money we're paid for it.
For example, despite making over $500k last year, we know your employer thinks you are producing more value than that, because otherwise they wouldn't pay you that much. You would be a drag on their income statement otherwise. What this means is that even if you donated 100% of your salary to charity, you still aren't taking advantage of the leverage of what you can build, vs. the fixed amount you can earn.
If instead, you choose to work on something which is inherently good for society, society at large benefits from that leverage. You might be paid less, say $200k instead of $500k. But since the positive value you produce is leveraged you could be contributing, let's say, $1M of positive value for society - $200k to pay you to live in the bay area ($800k net positive value).
Just something to think about.
If I increase online sales by 0.1% through optimizing something, I am worth millions of dollars to Amazon and nearly nothing to Joe Schmoe with a small Shopify site.
Yes, but software skills are fairly fungible. Just because you currently work on ads doesn't mean that's all your skills are good for, or even that you need to work anywhere in ecommerce.
The reason that I work (as opposed to https://en.wikipedia.org/wiki/FIRE_movement) is so I can donate, which is why I start with that piece of the explanation.