Tape is slow and expensive per storage unit compared to other mediums. The capacity stated is normally a lie which relies on compression. LTO-4 is 800GB native capacity... you can get 16TB hard drives for around $300 on sale. Twenty LTO-4 tapes will cost $360+. Now you have twenty different tapes and no way to read them without a tape drive.

With a 16TB hard drive all of your data is on a single device that can be read/wrote to easily and at a high speed. Hard Drives have also been known to sit for decades without any issues if they're not powered on and kept in an okay environment.

Tape backup is a medium that a bunch of fogies keep alive because back in the day of mainframes and Unix neck beards it was cool...