Criticality ECC for mat. calculations?

Question

RAM

Please tell me what is the real criticality of ECC for any mat. calculations with double precision, for example, and more specifically, the very cause of errors in memory ... After all, in theory, if you put a powerful uninterruptible stabilizer and a good power supply that smooth out all voltage surges in the network, then in theory there should be no jumps in the computer's internal network . And if you put this computer in some thick-walled lead case or something by analogy, then randomly flying neutrons, in theory, should not bother? It is so?