The genesis of this is when Apple moved from Intel to their own chips.
They used to use completely new names for new designs and then variants of that name for variants of that design. As in Sandy Bridge and then Ivy Bridge. Haswell, then Broadwell. Skylake, then Kaby Lake. Then Coffee Lake. Then Cannon Lake. 10 years later now they're still doing Lakes. It might not have much relation to the technical design but it gives the impression they gave up on new things.
Sometimes naming is just naming. No further depth or symbolism.
Skylake is when things started to go south, outwardly facing. But it was even long before that. The rot happened in the foundry side and it grew for a very long time, silently, because of how little competition existed.
Everything thereafter was pain.
Sure, the Core 2 series ultimately, after a long gap, put them back on the rails at least, but Intel missed big iron and panicked.
Everything else since has been about desperately squeezing x86 into every niche, even when it probably shouldn’t be. That the Core 2 series gained an Apple-shaped halo is lucky for them, but the reality is that they have been on the back foot at some level since the failure of IA-64.
They needed to get themselves out of the hole by using AMD’s architecture, and they have been a polar bear on a large but shrinking iceberg ever since.
Sold it twice.