No, the above photo isn’t showing you some kind of powerful dust accumulator; they are dusts on a laptop CPU heat sink after three years of use that has made the laptop unusable due to the frequent thermal shutdowns.[Source] It is not uncommon that the computer breakdowns (especially desktop with ATX chassis) are associated with overheating problem, and most of the time it is due to the long term accumulation of dusts within the desktop chassis (unless you have a dust-filtering chassis). If you have no idea on how the dusts can cause overheating, I would suggest you to read this article in Wikipedia, there’s lots of information related to the computer cooling.
Thus, overheating is one of the major issues that can cause the computer lifespan to be shortened. To prevent the shortening of the computer lifespan, one can always remove the dusts accumulated within the chassis (including the dusts stuck on the active cooling fan) frequently; however, it is not too ideal to do the dust cleaning every single week (because I know you have some other better things to do), so you would require some indicators from the computer itself, telling you that a dust cleaning is needed, and for this purpose, temperature monitoring software comes in handy.