It does seem that computers are approaching the limits of needing further hardware upgrades for most activities people need to do - there is some real horsepower in these new machines, not sure what it will be used for, or whether we will need further upgrades in the future. It seems unlikely. I am still using a desktop machine built in early 2008, but it cannot ( or Apple doesn't support ) the latest OS upgrades.
Watching the new iPad pro render games complete with sweat droplets on the players faces was remarkable even if not necessary. The images looked photographic, not like the crude graphic images games once had, really amazing realtime rendering on 4K monitors.
The new Mini with 3 GHz 6 core 8th Gen i5, 512 Gb SSD, and 64Gb of 2666 MHz DDR4 SO-DIMM memory sound like real beasts with a great set of I/O ports including T3, HDMI 2.0, USB 3.0, 10GB Ethernet, audio and costs ~$2800 - That's about what we were paying for desktop computers 30 years ago but what a difference in performance. Yes, you can buy computers for $500 bucks these days, but not with these specifications I don't think.
A basic Mini with 16 Gb RAM and a 256 GB boot SSD is only $1299, so yes, I think you can recommend them to a friend who wants a good quality high performance modern machine running Mojave. JMO