Adafruit products work as advertised, and are very well documented. Sparkfun is similar though their level of documentation is (IME) a bit more hit and miss.

For rando parts you get from rando vendors, it’s pretty common for schematics to have mistakes, pulldown resistors to be kind of off, and other components to be low quality.

For prototype development work, I’d rather spend a few dollars to have reliable parts that can be easily reordered than spend hours or days tracking down issues in parts that can’t always be reordered.

For post-prototyping and production work, you’re probably spinning boards anyway, and your choices and risks are pretty different.