Have you ever lived in a situation where downloading the entire Bitcoin blockchain from the Internet, and keeping up with blocks, would be cost-prohibitive in terms of bandwidth?  It is not a rare situation.  Not a corner case.  I think that the worldwide majority of people are probably in that situation.

Satellite TV dishes are ubiquitous.  Surprising and disturbing, but true.  They can be repurposed for this, with a few parts that fit into a poverty-level budget.  Now, at least, you can have the BYOB security of consensus-validating the blockchain yourself.  To make transactions, use your mobile data connection that has kbps speed, and costs money you can’t afford billed by the kilobyte.  Although it is not ideal from a decentralization viewpoint, it gets your foot in the door.

Still makes no sense?

Blockstream’s advertised primary use case for Satellite makes excellent sense.