ARM is hardly a "good thing". These things rise and fall almost purely by chance since the differences between ISAs are menial at best. If the stars had aligned differently this could very well have been a SuperH world. Or a MIPS world.
None of those 3 even tried to have a product for applications with low cost and low power consumption.
The only competition was from Motorola/IBM POWER (and MIPS in some niche products), but neither Motorola nor IBM ever tried to offer low cost products.
During 2000 to 2005, I have ported some products with embedded computers from POWER to ARM.
The porting was not very easy, because the ARM CPUs had much lower performance, but they were much cheaper, so the conversion was done anyway.
The ARM advantage has always been in its business model, which created a lot of competing CPU vendors, willing to give you the best price, not in any technical advantages of its CPU architecture.
The NVIDIA acquisition certainly threatens this business model, despite all contrary claims of the NVIDIA management.
Alpha and PA-RISC died before the smartphone revolution (end 90s vs mid 00s). x86-32 killed them, before AMD64 (x86-64) took off.
Laptops were all x86-32/64. There has been an UltraSPARC laptop (one AFAIK), and Apple switched away from POWER because of power inefficiency. Also before the smartphone revolution.
Intel was busy with Moblin and PowerTOP back in the 00s. This before iPhone.
MIPS and RISC-V also exist. Without ARM it would've happened but slower/later.
This is ridiculous. ARM was already pretty much well-settled-in in the PDA way before the smartphone, so it definitely didn't "single-handedly made it happen". And during the early PDA era, when they got settled in that market, it most certainly did not win due to "low power draw". Back in the day where SH(-3) PDAs where still a thing, the battery life was measured in days out of 2 AAA cells (even for ARM devices). That was destroyed due to forced backlight usage in most screen techs rather than any change in ISA.
Today MIPS is still used in network devices, SH is still used in things like optical drives, SPARC is still used on some servers, x86 is still used on many servers and desktops and mobile devices, and so on and so forth. Do you think that there is something technical that warrants the choice of these architectures for their usecases ? Do you think that there is something in SH that makes it a better ISA particularly for CD-ROM drives ? Or that there is something in SH that made it a better ISA for some videogame console generations, then something changed and the better ISA was PPC, then ARM, then x86 again ?
It's mostly arbitrary marketing decisions, which manufacturer happened to be doing well that day, and some "historical reasons"/network effects which define these choices. There's very little difference at this ISA/architectural level, and a lot in the actual design and manufacturing level, where ARM is not doing poorly but hardly shines. Apple, Intel, AMD, Qualcomm, even nVidia all do better than ARM there.
If we the wind had blown even slightly differently some day 20 years ago, we may very well be using anything else, even say Itanium in our smartphones. And before you complain that Itanium/EPIC are hardly suited for low power, remember that Transmeta made their money selling _low-power_ VLIW processors emulating x86 instructions. And actually they were lower power than their x86 competition those days. Perhaps Torvalds would still be there rather than making Linux...
Nvidia had at least two generations of Android tablets. Intel had several as well. These aren't smartphones, but they did have options for cellular modems, and there's really not much difference. I've got two tablets at home, one with a 3g modem and sim card slot (a family friend got it free from at&t). Whine I'm not aware of AMD making processors for any mobile devices, there's also nothing stopping them.
No, you can't buy either such device today, but reason they lost out had nothing to do with them being inappropriate for such use.
There were many other CPUs with the same or lower power draw.
The advantage of ARM has always been the cost. For given requirements of performance and power draw, you could find much cheaper ARM CPUs than the existing alternatives.
This happened because there were many competing ARM CPU vendors.
Motorola could give you a PowerPC CPU with the same or better performance and power draw, but they were not willing to lower their prices, falsely believing that there are no alternatives.
Therefore everybody abandoned the other CPU architectures and switched to the cheaper ARM solutions.
I'm sure many companies could do low power performant and cheap chips when high resolution small screens, lithium batteries and large capacitive touch surfaces matured enough to be harvested.
The thing is only Arm did actually designed appropriate chips at the right time and licensed those designs in the best way possible. Arm was IBM PC of the smartphone era and I don't understand how people might not appreciate that.
It's better to create a better thing first, even unfairly, and let it outcompete the incumbent.