Hi Alice,
it would be rather expensive, and slow. However, it also would be somewhat comparable to a patent register, or a land registry. Filing a patent is much slower, and much more expensive than inscribing an ordinal on the bitcoin blockchain. If someone has something important to say, he can certainly value it with some satoshis and minutes. We could also use a hierarchical structure for topics, similar to a patent classification code system, or the HS codes used in shipping.
best, Bob