I don't think thats a good point. I mean I can probably make a console application using .txt file on disk as the database and scale it to handle large websites.... if I had spent $100M on servers and 10 years of my life. Almost anything is possible with most of the technologies out there. But its about using the right tool for the job.

Stackoverflow is huge, its built with SQL server. If they had for example used mysql they would probably have had to hire 2x engineers + spent twice as much time tuning and tweaking.

All those top1000 mysql sites are heavily customized and tweaked to perform as well as they do. Using other modern technologies may had saved them 1000 of hours and money.