Due to physics, and the complicated fabrication process. It's harder to fabricate a CPU at a smaller node. The problem is complicated by the size of the CPU you're trying to fabricate because errors pop-up more often at smaller nodes.
So a smaller CPU, as TSMC has already printed several at 7nm, is easier to print than Intel's massive monolithic CPU's.
"A second reason for the slowdown is that it’s simply getting harder to design, inspect and test chips at advanced nodes. Physical effects such as heat, electrostatic discharge and electromagnetic interference are more pronounced at 7nm than at 28nm. It also takes more power to drive signals through skinny wires, and circuits are more sensitive to test and inspection, as well as to thermal migration across a chip. All of that needs to be accounted for and simulated using multi-physics simulation, emulation and prototyping." https://semiengineering.com/7nm-last-major-node/
But, using EMIB Intel could stitch 14nm+++ parts with 10nm parts creating hybrid CPU's until they've perfected the 10nm process to print their entire CPU's on 10nm in a competitive cost effective manner.
The question is, can they do this before AMD prints Ryzen on 7nm? AMD has an advantage here, Ryzen is 1/3rd the size of Intel's Coffee Lake.
Regardless I heard a rumor that Intel is switching to modular CPU's in 2020, to compete with AMD, although I have no idea if this was a joke or not.