Definitely not true in my experience, and I would think if it were true, most pages would be "slim and efficient". Where is the business value in doing anything else at that point?

The GP might not always be true, but no, we would not have slim and efficient sites, because of push web developers get to include all kinds of unnecessary tracking and in general bloat on websites.

> Where is the business value in doing anything else at that point?

You think developers prioritize business value? That isn't how employment works.

Static html sites are so easy. You can write one by hand in five minutes and it can run on a toaster. There’s more business value in ads and dark patterns.

Nothing prevents adding adds, trackers and dark patterns in a static website, I would assume most of it is served by 3rd party servers that handle the dynamic widgets. Isn’t that easy to insert in an otherwise the static site?

To be clear, not saying this is a good thing, just don’t see what prevents avoiding much of the bloat on top of that which supposedly adds “business value”.

The "business value" is that it is easier and cheaper to find a handful of scriptkiddies who think everything has to be done in JS, run after the latest hype, and don't even know you can send a form using plain HTML, than it is to get competent, educated devs who know when JS or even a frontend framework is the right tool for the job.

but can it do feature x that generates more $$$ ?

True but only if you know how to. Also slim will 99% of the time be less code too.

It's very situational. If you're talking about writing a static site generator or handcoding a web page, that's mostly true, although if you're trying to not just be efficient, but as efficient as possible, things like optimizing assets are a small but additional step.

If you're maintaining a web app over a period of years, it takes at least some effort and time to keep it slim and efficient because small inefficiencies here and there start to accumulate and these tend to be more demanding even in the best case.

There are some antifeatures that Dan Luu identifies, like dynamically unloading content, that probably take a considerable amount of time to implement while degrading both the user experience and efficiency, but I doubt avoiding those is enough to ensure good performance on more complicated projects.