At the time the article was written, WPSOLR was already delivering search from The Apache Software Foundation #Solr and Elastic #Elasticsearch.
But since, we’ve integrated OpenSearch Project, Algolia, Google Cloud Retail search and even made a big leap towards AI search with Weaviate‘s vector database (and soon Vespa.ai).
All those search engines can be accessed from hosted services, therefore no special installations are required on WP Engine’s hosting side.
For WP Engine sites with lots of traffic, like WooCommerce shops during #blackfriday, using an external search engine compared to using MySQL leads to less CPU/memory usage and a far better scalability.
Especially considering that caching is not an option for search.