I have read external hard drives that sat unused for 15 years. Hypothetically the bearings might dry out or something but I haven't seen one fail.

One the other hand I have chronically had problems with tapes I couldn't read, had spots of data corruption, or that took 18 hours to restore a 1500 byte file.

Part of it is that the use of tapes is less routine so it is a common mistake to think you wrote a good tape but you didn't check it and it's unreadable.

Another competitor for LTO tapes is BD-XL, which is more expensive per unit TB but the drives are cheaper.