The sibling posts may have forgotten about laptop variants like the i386SL, i486SL, and the IBM 386SLC and 486SLC. These were lower voltage, lower power, and included power management features that weren't present in the mainstream SX/DX chips. There were cmos variants of earlier chips as well that used less power too.

That doesn't mean all laptops used these, I'm sure some laptops used desktop chips.

It wasn't really necessary to have a special lineup of laptop CPUs because the base CPU power consumption was already low. 486 were using around 4-5W, if I recall correctly. Mobile CPUs really became necessary when the megahertz race started and power consumption increased to much higher levels.

They had bog-standard CPUs in most of the cases, because their power draw was quite low.

You might be too young to have known that time, but 386/486 just had a tiny heat sink on them and that was all; the real power consumption boom and the serious heat dissipation systems came down the Pentium line.