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?
You would still have to download the entire blockchain if you wanted it as the transmission is only for new blocks. It is broadcast only so if you have a block with corrupted data, there is no way to request a re-transmission so you need an alternative method to obtain them anyway. Their transmission footprint means that most of the world has no access to it anyway. Much of the third world has better wireless connectivity than the first because they didn't start out with POTS and have been rolling out state-of-the art stuff from the go and they can use cheap off-the-shelf equipment and not have to install expensive satellite equipment.
Yes, it makes no sense. As evidenced by the fact nobody is using it. There is no market for it because it's poorly conceived.