I had an argument a few weeks ago because our page took 4 serial requests before content appeared. I argued - with solid data - that it should be 1. If we could manage that, cold load time would ~ halve.

Where's the benchmark or at least the numbers? If not, that's not proof of anything. Nothing to argue about. I'd just laugh.

> You can't win against cargo-cult coders

You don't need to. Unless you're not in control or don't have influence then whatever. It shouldn't be about "winning". It's either some vote (hence influence) or there's a process e.g. PoC with backed numbers.

I like to fight this kind of asinine "push back" by simply reversing the time order:

Here's an app that does 5 CDN-cached requests of its JavaScript. Demonstrate why disabling the CDN cache and splitting that into 500 individual requests is better.