"Chiplets" doesn't adequately describe the situation. The packaging tech Intel is using for these new laptop processors is far more advanced than the packaging tech AMD has been using for any of their chiplet-based consumer CPUs.
The packaging tech actually has to be less advanced to be economical.
"That was the first generation. Xilinx worked with TSMC on CoWoS. Their codename was CoWoS. It’s a funny name for TSMC’s silicon interposer. That was a first-generation advanced package technology... I talked to one of their VP. I talked to them many, many times, until one time, I had dinner with [a Qualcomm] VP, and he just very casually told me, he said, you know, “If you want to sell that to me, I would only pay one cent per millimeter square.” One cent per millimeter square. He said, “That’s the only cost I will pay for it.” I said, “How come you didn't tell me earlier?” He said, “You should know that. Why I should tell you? You should know that.” ...Our second generation called InFO meet that criteria and it was sell like a hotcake. So that one word saved my life and the InFO was why Apple was hooked by TSMC."
The packaging AMD uses for their desktop processors is cheaper, and much worse in terms of performance and power efficiency: moving data between chiplets is too expensive to work well for a laptop processor. (That hasn't stopped them from shipping the latest version in a BGA package for use in massive gaming laptops to compete against Intel's desktop-silicon-in-laptop-package parts, but the idle power draw still sucks.)
IMO Intel has over-engineered Core Ultra. The packaging is very advanced but what if that complexity isn't needed? Never send a bunch of chiplets to do a single die's job.
In the short term, this makes them much less dependent on their first EUV process, since that's now only used for a small chiplet of just the CPU cores, while the rest is on a more affordable and reliable TSMC process. That risk reduction may have been critical to being ready to ship this year.
In the long run, I think they also need this kind of packaging to become affordable enough to use across their consumer lineup, not just for the exotic data center parts. Making a big change like this mobile-first and bringing it to desktop in a subsequent generation worked out alright for them with Ice Lake and their 10nm process, so I'm not surprised to see them do it again.
