“Its built on top of the LMDB key-value store and lives as a 35 MB binary when installed on Ubuntu or MacOS.”
One 35 MB binary gives you stemming, synonyms, ranking, faceting and a web UI with sane defaults. Elasticsearch wants a JVM and a cluster to do the same job. Most sites need search over a few million records, not a petabyte. They have been buying the bigger tool for years.