Perhaps not on Linux. You don't need to run Linux on SBCs. At least not exclusively.
Some SBCs also contain additional non-ARM processors on the SoC, which could be used for the purpose of data acquisition.
For example Orange Pi has H3, which contains OpenRISC core that can run at 300MHz or so from code located in internal SRAM. I haven't tried yet, but I guess you can get pretty consistent results with this approach too: Main cores running on Linux processing the data, OpenRISC accessing GPIO and reading the data in a tight loop, throwing them to main memory into some ring buffer, or into part of the SRAM.
Well, I was talking about the Raspberry Pi Zero specifically, which doesn't have those RISC cores.
One particularly cool Single-board Computer (SBC) is the Beaglebone Blue. The Beaglebone Blue came with "PRUs" (Programmable Realtime Units), which seem similar to the OpenRISC core you are talking about. Such "embedded microcontrollers" exist because the main computer. There are also a hell of a lot more GPIO pins, ADCs, Servo-channels, Motor-controls, and other such stuff to assist the robotic designers.
No need for "Realtime" Linux either, if you're focusing on the PRU / alternative cores to do the heavy-lifting. So I didn't want to discriminate against SBCs as much as I wanted to highlight the importance of low-latency and consistent reads off of pins. Two things that the Raspberry Pi is pretty dismal at doing.
Its fine, ycombinator is a web-technology, software-focused message board. YCombinator cares about web-technologies, keeping up with Linux Kernel patches, and the like. And that's good and important.
However, embedded and microcontroller features are often ignored, despite embedded topics popping up around here pretty often. So I felt it necessary to bring up the compare/contrast.
With regard to the PRUs, I don't think the BB Blue has anything the BB, BB Black, and BB Green don't. They all have the PRUs. It's a function of the AM335x Cortex-A8 SoC.
At this point, you need a time machine to get a BB Blue, anyway.
Some SBCs also contain additional non-ARM processors on the SoC, which could be used for the purpose of data acquisition.
For example Orange Pi has H3, which contains OpenRISC core that can run at 300MHz or so from code located in internal SRAM. I haven't tried yet, but I guess you can get pretty consistent results with this approach too: Main cores running on Linux processing the data, OpenRISC accessing GPIO and reading the data in a tight loop, throwing them to main memory into some ring buffer, or into part of the SRAM.