[jillesvangurp]

They are part of the hype. Lucene has vector search capabilities. Elasticsearch and Opensearch have support for that (slightly different implementations). I assume solr has similar capabilities. The combination of traditional search and vector search makes a lot of sense from a cost control point of view. Vector search at scale is expensive. The smaller the result set, the cheaper it is to do vector search over it. So using a cheap traditional search to limit the results before you run vector search makes a lot of sense.

Also, bm25 holds up well against vector search. A well tuned model can outperform it but many off the shelf models struggle to do that. Vector search is a useful tool but so far it's not a one size fits all solution that "just works". It's something that can work really well if you know what you are doing and with a lot of tuning. With things like Elasticsearch you can try both approaches.