Resolved How should a MacBook react to a broken fan?

My (early 2015) Macbook Pro's fan got broken. I first noticed the computer getting awfully slow when stressing it a bit. Also the Kernel Task went up to a few hundreds to thousands percents of cpu usage. After I noticed the fan reportedly was basically idleing around at the same time I ran the Apple System Diagnostics, which confirmed there might be a problem with the fan. I opened it up and yes, it was blocked, couldn't spin. I ordered a new one and now everything works as fast as I expected.

But: I'm wondering why the mac did not shut down, but instead just got much slower? I assume the cpu got clocked down. I still could work almost normally with a little (sometimes much) more patience needed from time to time.
Is this intended? How exactly should the mac react to a not working fan? (Even with no fan, the cpu never got above 95 degree celsius.)