Difference is a crawler paces the requests, respects robots.txt and rate limits, and doesn't typically invoke 50-100MB disk I/O per request.
Like I don't mind automated access to my search engine, I even offer a public API to the effect, that you can in fact hook into SearXNG. What I mind is when one jabroni with a botnet decides their search traffic is more important than everyone else's and grabs all the compute for himself via a sybil attack.
It is a metasearch engine. So it uses other search engines. The point is to let multiple use it, so that Google et al. does not know who's using their service. Ie. it is a gloried proxy.
Honestly, I just use Kagi. Though I need to find some way to limit my searches to 300 per month.
