Not an expert but I’ve heard this too. However - if this IS true, it’s definitely only true for the biggest drives, operating in huge arrays. I’ve been running a btrfs raid10 array of 4TB drives as a personal media and backup server for over a year, and it’s been going just fine. Recently one of the cheaper drives failed, and I replaced it with a higher quality NAS grade drive. Took about 2days to rebuild the array, but it’s been smooth sailing.

The bit error rates on spec sheets don't make much sense, and those analyses are wrong. You'd be unable to do a single full drive write and read without error, and with normal RAID you'd be feeding errors to your programs all the time even when no drives have failed.

If you're regularly testing your drive's ability to be heavily loaded for a few hours, you don't have much chance of failure during a rebuild.