Exactly. The PO purpose of single use seals is to create a framework for generalizing the idea, as well as scaling single use seals.
Complaining about that is like complaining that OpenTimestamps is useless because you always could timestamp data with Bitcoin.
No one has ever presented OpenTimestamps as a new cryptographic primitive or hinted that it could work without something-like-Bitcoin underneath.
I'll say it right now: OpenTimestamps could absolutely work with something unlike Bitcoin underneath. Hell, trusted time-stamping with it (specifically with one-time-use disposable keys) is on my to-do list. And widely-witnessed time-stamping has already been implemented.
Single use seals also could be implemented in a variety of ways. That's the whole point of coming up with the idea: to separate the cryptographical primitive from the implementation.
