They are talking out of their ass.
SSD will speed up loading times and booting times by a lot, but once ingame it does nothing more compared to a HDD
What you need for DCS to run 1080p
Intel i5 CPU (DCS doesn't take advantage of i7's hyperthreading and AMD CPUs are trash in comparison)
GTX 970 or R9 380X or better.
Don't skimp out on power supply. Do some research, get a Tier 2 PSU at least, http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html, you don't want your $600 dollar rig to burn out because you bought a crappy Corsair CX series PSU or even worse.
SSD is a quality of life improvement especially if you have your OS and DCS on it as out of game time will be non-existant.
16GB of RAM, DCS likes to hog RAM, especially NTTR, speed of ram actually doesn't affect performance that much according to benchmarks.
Running 4K at 60fps reliably is not possible with anything but a 980Ti or Titan.