When people say "ergonomic chair" all I can think of is those stupid "tuck your knees under you" backless chairs from the late '80's and early '90's that had to be taken off the market as they were causing people to have feet amputated and even end up with aneurysms from the clotting caused by applying body weight on an area of the shins not designed to support it! In other words what happens when a back specialist completely fails to account for ANY other biological factor in their "design".
Much like "organic foods" or "homeopathic cures" it strikes me as scam artist hoodoo voodoo created to do nothing more than fleece the feeble minded's wallets.
The design of the chair evolved over centuries of human use, and pardon the pun but I'll take evolution over "intelligent design" any day. Particularly when those who fall for it are more often than not lacking in the 'intelligent' deparatment!
I have only two requirements for a chair:
1) Comfort
2) Adjustable
Anything that's supposed to fit "everybody' without adjustments falling into the "flaw of averages" -- which much like false simplicity causes more problems than it solves.
For a fun read on the "flaw of averages" check out this snippet from a book on the topic, and how it cost lives at the start of the jet age when it came to cockpit seating.
thestar.com/news/insight/2016/01/16/when-us-air-f…
If you're working in UI and UX, I consider the book that's taken from:
harpercollins.ca/9780062358363/the-end-of-average
... to be a "must read". The best of REAL "ergonomics" is anything the end-user can adjust to their own needs. Anything else is snake-oil peddling dimestore hooodoo, five and ten voodoo.
The comparison to "organic" is apt, the word has a real meaning, but it's been slapped onto things as a marketing ploy and bandied about by so many know-nothing halfwits, morons, and fools that the mere presence of it is now a flag for distrust.