One could argue it took ten years for Intel to have enough competition from ARM to actually wake up and do something again.

I don't care, I got a 12th gen i7 with integrated graphics (in the weird time window and edge case where Intel was ahead of AMD again for a bit) which is super fast and was way better priced then Intel used to be.

Comperition is good for consumers.

Agreed - I think it’s indicative of a less insular attitude which can only be positive.

Well, desktop and laptop PCs didn't have the extreme power constraints that mobile devices had.

So why are Intel using it now?

The goal posts moved since then.

Which goal posts? Competition from Apple?

No, consumer demand. It takes years to design, test and prepare for manufacturing a new CPU architecture, so Intel had their big-little in the pipeline long before Apple came out with the M1, same how it took Apple over 10 years of iterations to get to M1.

The real question is what is AMD gonna respond with?

It’s a strange argument that customers didn’t want better battery life from their laptops until now.

All credit to them now but lagging 10 years behind Arm in having this is not impressive.

I think you're mixing up some things. I couldn't just buy an ARM chip and plug it in a desktop PC or laptop and plus, the ARM chips, big-little or not, we're terribly underpowered 10 years ago compared even to Intel Celeron.

So calling it 10 year lagging because of a feature that had no relevance in the PC space back then is a misrepresentation.

Big-little made it to the PC market now since modern CPU cores are powerful enough that even low performance ones can still run a desktop environment and browsers well enough without stutters. That was not always the case 10 year ago, so consumer demand was always optimized around maximizing raw performance.

So, the fact that ARM had this feature 10 years ago is larglely irrelevant for this argument

It's ARM's performance improvement at the top end in the last 10 years that changed the landscape for the PC industry to a degree, not big-little.