Not just old tech. But old tech made new again. Think about how much server-side web hosting de-complicates websites. If you had to start with a blank linux box, PHP is still one of the fastest ways to get something with a shopping cart functional to this very day. If you are into new-fangled shiny shit and can't be bothered with old, proven tech, look no further than Blazor Server for 99% of the same idea. But also way better because you have C# 8.0 and one of the best IDEs + first-class debugger support at your disposal.

In some circles, you might even be accused of being a boomer for using SQL. I think a lot of developers are missing out on just how much runway you can get out of SQL and libraries like SQLite. You would also be missing out on one of the greatest breakthroughs in the history of computer science with regard to our ability to model problem domains and perform inhuman queries against them with millisecond execution times. But hey, maybe machine learning and mongodb are working for your shop.

The final thing a lot of people miss are old ideas. Put your entire application on a single server somewhere, and all of its dependencies live in the same box. Optimize the vertical before you rewrite for horizontal, because 99% of the time you will go bankrupt before you get as big as Netflix so it wont matter anyways. Plus, you would go bankrupt faster anyways by chasing delusions of web-scale grandeur when you could have had the MVP done 3 years ago with just a simple SQLite database back-end and a T3a.micro. More likely than not you would have discovered it was a bad idea to start with and could more quickly move on to the actual thing you should have been focusing on.