If airflow travels through something and you don't work in a dust free environment, it needs to be cleaned periodically.
It's too bad that OS' weren't more wise to this. Right now there are certainly millions of desktops and laptops that are running far below their potential because it is forced to thermally throttle, yet there is no indication for the user beyond things being slower than it once was.
I get it, just like an iPhone can track the health of an installed battery, an oem laptop manufacturer should be able to track the effectiveness of a cooling solution and know that the fans are worn or dirty or you've blocked the vents.
A temperature display itself probably wouldn't be of much use because the CPU will reach an operating temperature and modulate the frequencies/boost to avoid exceeding it. One user could be enjoying full performance at that temperature, while another user is running at 1/10th the speed.
The OS does see the perpetually fluctuating frequency state of the processor, though, and can monitor it over time in a correlation with the temperature and display a simple aggregate performance metric, flagging as a system alert when performance falls below a set threshold. I've had relatives whose system saw a dramatic, very noticeable usability improvement after a couple of quick bursts of compressed air.
Do we have to choose one or the other? This seems like a false dichotomy. How about no malware/badware and optimal heat dissipation? That's the route I go. I've yet to acquire malware from a can of compressed air and a Phillips screwdriver.
And the performance impact can be absolutely extraordinary. I've seen systems go from barely functional to completely decent via a simply cleaning. Note that there were no faults or errors in the former case, it simply was forced into perpetual thermal throttling. In modern processors this case halve and worse your performance with ease.
It's too bad that OS' weren't more wise to this. Right now there are certainly millions of desktops and laptops that are running far below their potential because it is forced to thermally throttle, yet there is no indication for the user beyond things being slower than it once was.