> In the past I guess they could blame Intel somehow,
It was fairly easy. Intel's released products often would not meet original spec, or once it was throttled to fit into spec it didn't have significant performance gains over the prior generation. Often they would go generations without the performance warranting the increased part cost.
> They've never managed to settle into any kind of consistent upgrade cycle there
They would like an annual incremental upgrade cycle and a five year design cycle.
Even without Intel, they still have supply chain constraints. For instance, even with their own silicon, they are relying on TSMC to be able to meet process and production volume targets.
Releasing chips on a new process will likely lead to really odd effects due to yield issues - for instance, having a new CPU show up first in products with lower sales volume. That includes tiering, either with things like a regular vs "pro" phone, or retaining the older model of computer while charging more for the newer version.
Right now they appear to be on an 18 month cycle for Apple silicon, which is driving their new hardware (either with a new machine serving as the launch platform of some new SoC, or a design revamp of a machine based on existing SoC).
Humorously, the only product which has had an incremental update so far is the MacBook Pro 13".
I suspect they'll eventually have a two or three year "architecture" tick for their Mac and iPad SoCs. Depending on those architectures and the upstream changes at TSMC, there might be a lot of different SoCs released against that tick.
> but they're not even releasing an M2 iMac at all.
I'd be really shocked if they don't release a M2 iMac, most likely in March.