The "rock on a rope" comment about older anchor types comes across as hyperbole, implying "new technology" anchors like the Rocna have made them obsolete.
I think the new generation anchors like Spade, Rocna, and Raya HAVE made older designs obsolete. Obsolete doesn't mean the older designs don't work any longer anymore than the advent of disk brakes on cars meant drum brakes don't continue to work; it simply means there is a much better solution available.
I drove a car with drum brakes long after disk brakes were on the market, but when I bought a newer car it for sure had disk brakes.
I've anchored in various boats with a cinder block and rope, grapnel, mushroom, CQR, Bruce, Danforth, Delta, Spade, and Rocna (that I can think of offhand). The new generation anchors are substantially better in the range of bottoms I have encountered in 35 years of sailing and five years as a delivery skipper.
The worst anchoring situation that I am likely to encounter involves a weedy/muddy bottom, often in a crowded harbor where you don't have any other options and have to work repeatedly to get past the weeds fouling your anchor to get a set.
A Rocna served very nicely along the Eastern shore outside Settlement Harbour (too shallow inside for me) at Great Guana Cay in the Abacos. No drama associated with anchoring and we didn't budge an inch overnight. We did get a lot of entertainment as charter boats tried to anchor near us on older design anchors and failed.
Now I'll be the first to say that technique is at least as important as the hunk of metal on the end of your rode, and I'd like to think I have more practice than the average bareboat charterer. Nonetheless, based on my personal experience I wouldn't spend my hard-earned money on anything but one of the new generation anchors or, for some applications, a Fortress.
Your money, your choice.