If you were focused on profitability, you wouldn't run Target CPA. Your marginal cost per action is going to be much higher than the target CPA, making your marginal acquisitions unprofitable, lowering your total profit. That's in the best case, if you have unlimited budget. In the unlimited budget case, Google is at least incentivized to bid on the lowest CPA users first. In the constrained budget setting, they can give you absolute garbage, and it's no skin off their backs. It's even worse if not all of the actions are incremental, which for an established company with unlimited budget is guaranteed.

The past few years, Google has been adding features that make absolutely no economic sense (assuming rational firms), but assuming that most of their clients are unsophisticated and then taking advantage of them has no doubt earned some Google Ads PMs huge bonuses.