Steve, in the absence of solid data that would be a valid consideration. However, in reality I typically run within a second or less of the leaders. I know why they are faster than me, and I'm satisfied that it isn't horsepower, it's talent behind the wheel. The top 10-15 of us usually are within two seconds on a 1:29 pace set by the leaders."I ran towards the front with that engine (typically top 10 or better in our 40 car fields) for a large part of that time."
But that could mean a person is typically within a couple seconds at the checkered, or much further back. I would say that a good driver can finish top 25% at most Majors with very similar engine costs, but that's not necessarily considered competative.
As for the peak power argument, again valid. But remember that we are all on the same engine and management system, and if the best SM minds in the country haven't figured out how to LEGALLY optimise the 1.6 for that, I'm not too worried. Could it happen? Could a no-holds barred effort show up and slaughter the field? Absolutely. Has it happened? Not yet. But then again, that can happen anywhere, any time. No rule can control spending.
As you said, and as I and others have said, it's the culture. Part of that culture is to respect the mission statement and the rules. Ours works. Others are welcome to duplicate it.