Can anyone explain to me the reason why Magento no longer recommend the use of catalog flat table. As per the official documentation, it's degrading the performance because of the slow/long SQL queries, but, why now? not in M1. Please give me any logical reason
My understanding is that this is due to the introduction of Elasticsearch support to Magento open source 2.3+. Indexing flat catalog has always been slow, the introduction of Elasticsearch simply introduced a more efficient alternative.