This is a huge problem with a lot of discussion about software development practices. Software spans an astronomically huge realm of scales and varieties, yet so often we talk about it as though it's a monolithic thing. As if you could talk about bacteriophages and pachyderms or cap guns and moon rockets in exactly identical terminology without any loss of fidelity in describing either.

It is very true that software development techniques and practices should differ, perhaps even greatly, depending on the nature of the project. It's most important to be able to have the experience and knowledge necessary to know when and where to use one technique over another rather than to just be a mindless sponge of advice.