While the speed increases weren't as dramatic, do note that even in single core speed, unlike the clocks would suggest the Ryzen 7 is much, much more than 1.23X faster than the P4. The P4 was a particularly fragile architecture, and achieved IPC on real code was typically well below 1, often closer to 0.5. The x3d variants of Ryzen have been measured at running above 3 average IPC on real, complex loads. So the single-core uplift from that P4 to a modern AMD core is about the same as from that 300MHz Pentium to the 3.8 P4, it just took 20 years, not 8. Of course, now we also have 8 times the cores.

A switch from the exponential regime to something immensely slower was a qualitative change. The difference is so vast that it's completely reasonable to say that clock speeds haven't changed a single bit since 2006 or so (and even for raw ops/s speeds, which have improved much more, it's debatable).

Clock speeds used to be going up in a straight line (the normal "interpretation" of Moore's law) - but once the P4 hit a (kind of useless 3.8GHz) we leveled off for decades.