Yes, early warnings about bad memory modules are probably the most useful ECC feature.
I have always used only ECC memory in any computer larger than an Intel NUC.
When the memories were new, they always had very low rates of correctable errors, e.g. one error after 3 to 6 months of continuous operation.
Nevertheless, I had several cases when a certain memory module started to have very frequent errors after several years of working fine. Due to ECC, I was able to identify it and replace it, before causing irreparable data corruption in files.
Moreover, in one case I had a laptop with ECC memory which seems to have used some poor quality SODIMM sockets. After being not used for several months (which made it more sensitive to air humidity, by not being hot as during use) it seems that the contacts of the sockets had oxidized so when using the laptop again I have seen very frequent memory errors.
Eventually, after some time wasted with investigation, I have scrubbed the contacts of the SODIMM sockets and I have reseated the memory modules, and the errors have disappeared.
ECC is somewhat less necessary in those laptops and small computers that have soldered DRAM chips, both because the total amount of RAM is small (the error frequency is proportional with the total amount of RAM) and because there are no sockets and long PCB traces (which are susceptible to electrical noise) between CPU and RAM.
At least for all computers that have socketed memory, there should have been a customer protection law forbidding the sale of such computers without ECC memory, because it is not acceptable to use a computer that may produce at any time undetectable errors.
I have always used only ECC memory in any computer larger than an Intel NUC.
When the memories were new, they always had very low rates of correctable errors, e.g. one error after 3 to 6 months of continuous operation.
Nevertheless, I had several cases when a certain memory module started to have very frequent errors after several years of working fine. Due to ECC, I was able to identify it and replace it, before causing irreparable data corruption in files.
Moreover, in one case I had a laptop with ECC memory which seems to have used some poor quality SODIMM sockets. After being not used for several months (which made it more sensitive to air humidity, by not being hot as during use) it seems that the contacts of the sockets had oxidized so when using the laptop again I have seen very frequent memory errors.
Eventually, after some time wasted with investigation, I have scrubbed the contacts of the SODIMM sockets and I have reseated the memory modules, and the errors have disappeared.
ECC is somewhat less necessary in those laptops and small computers that have soldered DRAM chips, both because the total amount of RAM is small (the error frequency is proportional with the total amount of RAM) and because there are no sockets and long PCB traces (which are susceptible to electrical noise) between CPU and RAM.
At least for all computers that have socketed memory, there should have been a customer protection law forbidding the sale of such computers without ECC memory, because it is not acceptable to use a computer that may produce at any time undetectable errors.