When did DC-DC buck converter modules become so popular?
15 years ago:

it wasn't as easy as today to order electronics from China (all these modules are made in China), like a DCDC converter module. Sure, you can design your own PCB but that will be more expensive than a ready made module. Also a module will just work (get the layout wrong and your design might not work as well).

electronics in general have become a lot cheaper, especially when you order from China

cheap microcontroller boards like Arduino were not yet available. Such cheap and easy to use boards get more people involved which increases the demand for all kinds of modules. Like DCDC converters.

not so many cheap DCDC converter ICs were available. Several Chinese manufacturers have jumped in and now dominate the cheap 4 or 5 pin DCDC converter IC market.


So low price and convenience makes these modules popular. I would not use a &quot;cheap Chinese&quot; module in a professional or mass produced design but for hobby purposes they are OK. I use them all the time. For professional use better quality (but more expensive as well) modules do exist.