My main work setup today is actually a diskless (X11-less) OpenBSD
Please be careful when you compare a technology choice of today with yesterday.
What Larry and I were arguing about diskless was based on the Masscomp WS-500 vs Sun-3 vs Apollo system of the same vintage. Pricing on the 3 systems (with a disk) and the same amount of memory (all three used the same 16Mhz 68020 processor) was $9.5K for the WS-500, $10K for the Apollo and $11.5K for the Sun. But if you dropped the disk out the system, the Sun's dropped to $7K and the Apollo's $6.5K (Masscomp could not because I refused to build it as I thought it was crappy idea for a real time system).
FYI: Sun charged another $5K for an add-in disk unit, although on the aftermarket you could get one that worked fine for about $4K [which is what we did to all the Stellar development systems when we discovered that they did not work as well as we had thought].
IIRC the memory was 4M (it might have been a little more, but not too much). The disk itself was on the order of 100M in size and was ST-506 based on, with an ST-506 to SCSI converter. I'm trying to remember when the 200-500M 5.25in ST-506 disk showed up but I think it was a little after that.
The point is the cost of the HW and configuration of the HW for all intents and purposes was the same between the three systems.
The difference really was the software. Each had made different choices... given their chosen markets.
Today, the HW allows different choices. Memory configurations alone, make diskless much more interesting. Ignoring a local cache, if you a RAM file system on a system like what I just described, it took up 1/4 of the memory you had.
Today, Linux and *BSD use 'ramFS' just to boot the OS - which makes perfect sense, today.
On the other hand, back in the day, on the Masscomp, we turned the cache off and 'borrowed it' as scratch pad RAM for the boot process (UNIX turned it on as part of turning on the MMU) because memory was such a premium and it might not be working. Diskless was cost choice in the old days. Today the price of the disk (SSD) (i.e. price/bit is so small) the 'cost' has more to do with power and space in the case and possibly portability than the price of the bits themselves. In theory a 'Chromebook' style system of today needs to permanent local storage.