IPC gains per generation are vanishingly tiny, if they exist at all. Skylake -> Kaby Lake, for example, had no IPC improvements at all. A very small clock bump to the various tiers was it.
Yeah - I remember when five year old CPUs were basically useless!
(Kaby Lake is basically a new stepping of Skylake - if intel wasn't having problems with new process nodes it likely wouldn't have been released at all, and if it was it would've been used for a one-off chip in the same generation ala the 4770K)
Even if you look over a large generation gap there's only a ~20% IPC improvement going from an i7-2600K to an i7-7700K ( https://www.hardocp.com/article/2017/01/13/kaby_lake_7700k_v... )
6 years & a shrink from 32nm to 14nm and all it can muster is +20%. Cores are just not getting faster by any meaningful amount.