Ta for the link. That is quite a discussion. The first thread is priceless (it turns out that grauenwolf isn't quite as authoritative as they first appear - fancy!)

Never underestimate how keen people can become about something they have paid £1,000s for. How on earth could a DBMS like MySQL/MariaDB or PostgreSQL possibly compare to the mighty Oracle money generator or MSSQL ... errrr ... money generator.

Just in case you wonder whether open source DBMSs should be taken seriously, try reading this: https://postgresweekly.com/ and this: https://mariadb.com/resources/blog