With the caveat that I might be slightly out of touch (I have nothing beyond the Pi4/400 and the last x86 mini-box I bought was over a year ago)…

IMO the key benefit of a Pi over an x86/a64 box, assuming you aren't using the IO breakouts and such, is power efficiency (particularly at idle-ish). The benefits of the x86/a64 boxes is computing power and being all-in-one (my need was due to my Pi4-based router becoming the bottleneck when my home line was upgraded to ~Gbit, and I wanted something with 2+ built-in NICs rather than relying on USB so didn't even look into the Pi5). Both options beat other SBC based options due to software support, the x86/a64 machines because support is essentially baked in and the rPi by virtue of the Pi foundation and the wider community making great efforts to plug any holes. A Pi range used to win significantly on price (or at least price/performance) too, but that is not the case these days.

I don't get how your argument infers from your parents comment.

To me it would be the opposite conclusion: stay away from ARM SBCs with proprietary firmware and just go Intel-x86 NUCs if you don't want surprises.

And yes, RPI was(is?) a proprietary-FW SBC as the Broadcom VideoCore GPU driver was never open sourced from the start and relied on community efforts for reverse engineering, which the rPI foundation then leveraged to sell their products at a markup to commercial customers after the FOSS community did all the legwork for them for free. Like so long and thanks for all the fish.

Meanwhile Intel iGPUs had full linux kernel drivers out of the box. That's why they're great Jellyfin transcoding servers.

It’s a combination of IP and deep institutional expertise. The 5G standards plus other important protocol documentation, for example, are on the order of fifty thousand pages, built on decades of experience with edge/2g, 3g, and LTE. That’s just the documentation on the protocol, the real secret is in the mixed signal ICs that require custom cell libraries which Qualcomm/Broadcom work with fabs to develop for their own use. The only other company of note in this field is Apple which bought the initial IP from Intel (which bought it from Infineon, another IC manufacturer), so we’re talking about something so technically complex that only the deepest pockets and expertise can make any headway. When Apple bought Intel’s modem IP, over two thousand employees transferred with the deal, to give you an idea of the scale.

That’s just the radios, which is their bread and butter. A lot of their other products have similar barriers to entry.

As the sibling comment noted, FPGAs aren’t even in the running. Ignoring their power consumption, the biggest FPGAs only have a hundred thousand or so logic elements. While its not easy to map that to number of transistors per se, even a legacy nodes are capable of much more complex designs than you can fit on an cutting edge FPGA. This really makes a difference even at the lower end because you have to get the timing right between all the different parts of your logic, and making everything smaller gives a lot more room for error (its a lot easier to put delay lines than to reconfigure a section of your design to fit closer to another section).

The range of their offerings is immense and I think each product should be evaluated individually to competition. But just as an anecdote from my company - to create a full spectrum DOCSIS signal our HW team used multiple huge FPGA chips, I think it was Altera 10 or something (device is EOS by now) and that only for the DAC (kinda), there were separate CPU, separate 10G switch, separate utility FPGA, separate memory, separate everything. And it had to be glued together with some insane mash of code on top of the FPGA blobs which not always work as expected. All in all it was a ten unit monster which used something like 4000W in steady state and a dozen of industrial coolers at max to cool it off.

And today that is replaced with a single relatively tiny in area chip (those old FPGAs were huge) from Broadcom, which does literally everything and complies with newest standard and uses tens of watts of power, and it is passively cooled. It's not quite the correct comparison since arch changed in the meantime, but if someone would build an exact replacement for that older big device using new chips and have the same specs, it would be half as big and use under 1000W or even less. And all software is ready to use without reinventing half of it manually.

But yeah, Broadcom's support is slow and opaque. and they will stall any non-major customer for month for almost any request, because they are prioritizing different tasks internally. It's like a drug dealer dependency and there is only one dealer in your town :) .