I don't see how those could work. Since bloom filters can have false positives, the counting filter could end up letting you remove an item that was never added, thereby corrupting the entries for other items in the process.
You're right. However, in cases where we know the maximum number of items we'd be storing, we can adjust the "bucket size" of each row. Quoting the above wiki link:
> Because the counting Bloom filter table cannot be expanded, the maximal number of keys to be stored simultaneously in the filter must be known in advance. Once the designed capacity of the table is exceeded, the false positive rate will grow rapidly as more keys are inserted.
