There are other reasons to use tiles:
- The optimal process node for CPU and GPU aren't the same. I don't know too much about this, but I've seen it mentioned several times, on different sites.
- I/O and SRAM benefit less from smaller nodes, so putting cache & I/O on an older node is more economical without much downside. AMD even uses TSMC N7 for the 3D cache chiplets in its Ryzen 7000X3D models.
- Limits requirements on production capacity of newest node, which might still be in its ramp-up phase.
- Cost savings, as newer nodes are now always more expensive (i.e. not derivative nodes, but speaking of meaningfully different nodes).
A further possibility is that production lines that would've been built for
Intel 4 are instead being setup for
Intel 3, which is a derivative node and thus can probably use most of the same equipment. This could lead to a faster ramp-up for it, and might be necessary for their aggressive timeline for Sierra Forest and Granite Rapids.