I'd venture the 12 PCIe lanes are this platform's main limitation. ASUS has an inhouse ASIC team to create PCIe switches/hubs to compensate (indeed, they created most of AMD's current Ryzen chipsets), but even Intel has finally upped their PCIe lane count to at least 16 (for the U series) and the H series is still 16 + southbridge.
One NVMe (4), one GPU (probably 4, since I cannot find documentation on AMD's lane/port configurations), one Ethernet controller (1), wifi (1), fast SD card reader (1), and that leaves one measly lane for anything else (LTE, second NVMe SSD, more USB ports via a bridge, etc). No room for anything like Thunderbolt 3. Remember, we are talking about a nominally 35W SoC here, not a 15W deal.
It is a 35W SoC, so a dGPU is more likely than not. Even in lower end gaming laptops, most GPUs are still hooked across 8 PCIe lanes (really only the MX150 is cut down to 4 lanes, sometimes 2). A surprisingly large number of them are connected across all 16 lanes. That is a bit wasteful, outside of applications that could benefit from PCIe bandwidth. I'd imagine most aren't run on a laptop, as I'm finally living in an era when Macbooks are no longer dominating EECS classrooms here.
Either way. a higher idle consumption that leads to ~~15% less battery life, in an age where laptop vendors are willing to cut ~15% battery capacity per generation, in pursuit of "thinner, lighter is better [and it is]?"
Even the idle power draw of a screen is now deemed too high, as is the WiFi card, BT, etc.
AMD's infinity fabric (internal version) is the culprit here. A solution designed for scaling to a 64 core server is not quite a suitable for a 4 core laptop and vice versa. Even on the Ryzen desktop chips, Anandtech has noted AMD chips spend more power in the interconnect than comparable Intel chips while spending much less power in CPU cores (that's how you know AMD has Intel beat on CPU cores... but they lose in actually getting data to and from those cores). AMD made the best choices they could, for a datacenter/workstation CPU. It may even be the best for future game consoles. However, this does not mean their choices are the best everywhere, even a market as large as laptops.
That is BS (IMHO). This smells much like the Intel deals with OEMs a decade ago, launching competing products with a delay.
Smells aside (even if it's not true), I think OEMs screwed themselves over, by omitting AMD HW in their machines for too long. Intel is still advertised as the one true processor, AMD being a cheap knockoff. This narrative being in place for a decade now, AMD machines are less marketable and OEMs are stuck with Intel for better or worse. Ryzen CPUs are truly competing, but I still overhear the same BS in Best Buy / Media Markt et al that was true in the Bulldozer days.
Slightly larger idle consumption (especially in the context of gaming laptops) doesn't really justify the 95% vs 5% market share of non-ULV processors.
Nowhere else can you find a gaming laptop powered by a Ryzen 7 3750H CPU and a Nvidia GeForce GTX 1660 Ti GPU — for now, at least. Asus continues to be the only OEM offering 35 W Ryzen H-class options even after half a year since the initial unveiling of the new processor series.