No, it was a very good point. Not everyone adds hashes to filenames, and to me it seems that you're right in that weird caching can break pages that way.
If indeed this is the case, subresource integrity needs a big warning sign about that. For me, your comment was that warning sign, so please keep posting while you're not awake yet.
Why would it need a warning? If the HTML provides a new integrity="" hash, then any cached version obviously wouldn't pass. Subresource integrity makes it easier to determine if a cached file has expired. The file can be permanently cached for any HTML that requests the same hash value(s).
If indeed this is the case, subresource integrity needs a big warning sign about that. For me, your comment was that warning sign, so please keep posting while you're not awake yet.