Of course there may be scripts using /filter that could use hash tables instead.
But - for example - as items of a hash table are inherently unsorted, everything related to "keep things in order" is a pain (especially regarding performance) or imposible to obtain via hash tables, besides other filter features or related actions like strip, ranges, fast "duplication" of a [part of a] dataset (window content), loadbuf/-save etc pp.
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