In practice, because Smartmedia reads from the large face readers require about as as Compact Flash which reads from one end.

In addition, CF uses IDE protocol and has more volume for more memory chips. Smartmedia uses a bespoke and initially proprietary format (plus two incompatible logic levels) and its thinness meant the spec only describes one and two chip variants.

But they seem to work fine when I buy them from ebay and use them in old electronics.