This will be true for a long time - the design constraints are so totally different it would be foolish to use the same design in desktop and laptop systems.

The most limiting thing is TDP, which in the highest performance laptop processors is still capped at 45W, whereas a maxed out desktop processor can draw 100W or more.

See these tables for i9, for example, compare Coffee-Lake-S (Desktop) with Coffee-Lake-H (Laptop) https://en.wikipedia.org/wiki/List_of_Intel_Core_i9_processo...