That's not why thin-and-light bothers me. Historically, ultrabooks and similarly thin-and-light focused devices have been utterly insufferable in terms of performance compared to something that's even a single cm thicker. But Apple Silicon seems extremely promising, it seems quite competitive with thicker and heavier devices.

I never understood why everyone [looking at PC laptop manufacturers] took thin-and-light to such an extreme that their machines became basically useless. Now Apple is releasing thin-and-light machines that are incredibly powerful, and that is genuinely innovative. I hadn't seen something like that from them since the launch of the original iPhone, that's how big I think this was.

That's not exactly true, just the other day Snazzy lab complained about a MBP M3 Max throttling and making a lot of fan noise.

Those are barely competitive with the heavier but more powerful gaming/creation laptops Apple's aficionados keep deriding (if it has a 4090 it's not even competitive).

They have focused on mobility (power consumption and size) at the cost of everything else.

For this exact reason their desktop offering is really not competitive with offering around the same prices in the PC world. The only thing they do better is size (considering you can make a 3-4L top of the line PC; the Mac Studio isn't even impressive) and power consumption. But who actually cares, even if using a desktop heavily its consumption is dwarfed by most other use in a typical house, so whatever?

Thin and light are indeed a small use case overall and people who care about that have a ton of decently good options in the PC world already. It's not like the performance per watt benefits of Apple Silicon is really that relevant to most potential customers. If one is content enough with such a laptop, using it for the typical light task, thin and light PC laptops are just small enough, silent enough and have good enough battery life for the most part.