I did not say that. I said that most metalworkers familiar with all the downsides (only 1 of which you are referring to here) would avoid using such an unpredictable, uncontrollable, uneconomical blast furnace entirely.

A regular blast furnace requires the user to be careful. A blast furnace which randomly does whatever it wants from minute to minute, producing bad output more often than good, including bad output that costs more to fix than the furnace cost to run, more than any cost savings, with no way to tell or meaningfully control it, is pretty useless.

Saying "be careful" using a machine with no effective observability or predictability or controls is a silly misnomer, when no amount of care will bestow the machine with them.

What other tools work this way, and are in widespread use? You mentioned horses, for example: What do you think usually happens to a deranged, rabid, syphilitic working horse which cannot effectively perform any job with any degree of reliability, and which often unpredictably acts out in dangerous and damaging ways? Is it usually kept on the job and 'run carefully'? Of course not.