The finer grained performance per watt vs silicon cost set in the context of use case is just lost in HN hardware conversations like this that ignore total cost of ownership, vendor politics and such.
Everyone is buying the tool that does the job, or building that tool if they want to make that large investment...
There's a difference in cost per flop at home and in a data center.
I'm updating my wiring and air conditioning for a 7x5090 workstation because having that power for experiments under the desk is worth the cost (and fire hazard).
If I had to build 10,000 of those I'd be banned by NVidia from ever buying their hardware again.
Considering HN started in 2007 I don't think your expedition will yield a ton from the heyday of Mac PowerPC. Apple shipped the last PowerPC hardware in 2006.
To me it seems some people developed some highly political or even religious views on tech. Truth doesn't matter as much as it used to. It's more of "I like the idea behind X, I think X is cool so X should be the best thing ever".