Do you realise that what you are saying is heresy; it could get you burned at the stake!

Well, of course. But man, you do realize that he's had to pay a price for what he purchased -- both in direct financial costs and in flexibility. In terms of cost: that particular model was up on the refurb site this afternoon (and already gone now); but if I recall correctly, it was somewhere in the $800 to $900 region. That's roughly the same price you'd have to pay for a new (non-refurbished) Intel Skull Canyon.
The Haswell low-power i5 CPU is fine, but it's already three years old at this point, and was not top-of-the-line even in its day. The Intel Iris GPU was pretty much state of the art for integrated graphics three years ago, but really isn't competitive today. That 8 GB of RAM will do fine for most applications, at least for now. And the fusion drive was a superb idea for its time, back when SSDs were incredibly expensive.
In short, that 2014 Mini was a decent machine for its time. But, due to Apple's design decisions, that machine will remain stuck with those parts forever. No CPU upgrade; no GPU upgrade; soldered-down RAM; nearly impossible to touch drives. And so far as I know, the price today is the same as it was back in 2014.
You yourself have noted that you are running a 2009 machine that you've upgraded to 5 GB of RAM. The default configuration for that machine, with only 2 GB of RAM, would be unable to run the latest version of OS X, nor many modern resource-demanding applications. But your Mini was designed in such a way to make such an upgrade possible (although I admit the enclosure was not designed for easy access

).
If someone with a 2014 Mini should find, for whatever reason, that they need a machine with greater resources, they have only one recourse: they have to pitch out their current machine and buy a new one. It is this extremely wasteful design decision -- a decision Apple has explicitly made for purposes of forcing users to upgrade more frequently, as there is no other performance- or economic-related reason to do so -- that has caused so much heartburn in this community.