I think he means most people after another PC use what they have lying around...
and if thats a sot one processor then thats good.
There are two types of slot one processor...
genuine Intel.
these are te ones that are cased in black plastic, some have only ha;f a plastic case, and a heat sink attaches to the actual chip, others might have a small fan assisted heatsink to help cool the plastic caseing.
Or Celeron,
these don't have plastic cases at all, and you can apply heat sink to the chip directly, the heatsink ataches with a clip that goes through holes in the processor card.
Slot one processors run quite cold (so thermal pase shouldn't be required.) certainly there is no point in putting the thermal past on the plastic casing.