Most computer users never monitor their cooling effectiveness at all. They get used to the fans spinning up when the computer is doing anything that THEY think

Most computer users never monitor their cooling effectiveness at all. They get used to the fans spinning up when the computer is doing anything that THEY think is non-trivial, even if it actually should be trivial. Then there's a smooth transition from "fans spin up but things perform normally" (the ailing thermal solution is able to hit targets without throttling) and "fans spin up and things perform awfully" (the cooling can no longer hit targets without throttling). This can be explained just by thermal paste drying out and caking up, no more mystery needed. I've had 12 year old "workstation" laptops (the copper cooling alone was heavier than some entire laptops are these days) which started spinning up their fans for seemingly no reason. I dismantled them, cleaned off the old paste, put on a fresh paste, reassembled, and haven't heard the fans once since then. The cooling was good on day one, it got worse for unavoidable physical reasons, and it's easy to fix if you know how. The problem is most users do not know this is happening and wouldn't know how to fix it even if they did. If they ask someone for help, 99% of the time they'll be told it's too old and they should upgrade.