In general, this point is absolutely correct, and regulatory capture as a mechanism to stifle smaller competitors is shockingly common.
But in the case of requiring brokers of political advertising to maintain transparency about the reach of that advertising - that seems far more palatable and far more in the public interest. If you want to play in that specific sandbox, you owe accountability to the public at a level where dynamics across election cycles can be analyzed.
Of course, all this is just a thought exercise, since the background of the original post is that Google is removing its archive because its response to the EU regulatory environment has been to pull out of the political ads market entirely on a go-forward basis. Regulations did not require it to maintain any historical archives, apparently, and so the natural consequence would be that Google had no reason to air its historical dirty laundry with no benefit to them at all.