To make CPU and motherboard break faster. = More sold CPU's and less motherboards for second hand market.
Agreed, saw a bad case of that not that long ago on this forum, dude had a $500 top of the line Intel i7 extreme K version cpu and was using the stock cooler, 2 years after the fact turns out the cpu at stock speed and voltage was dead, well half dead, computer still worked with the cpu if you didn't mind it crashing all over the place all day.
We found out this was the case cus he changed the cpu's to a back up i5 cpu and the conic BSOD topic stopped like magic, lol $500 cpu with $5 cooler, that made me angry to see that and it wasn't even my computer.
Though more volts more cooling and less mhz sometimes fixs cpus like that, at lest for a wile.