First understand that there are two types of guitar instruction: accompanying songs with chords, and instrumental guitar playing. You can't tell right away if a guitar method is teaching instrumental guitar or how to strum chords to accompany songs. There is a very big difference.

Instrumental guitar is hard, and if that is your goal, you have years of work and scale practice ahead of you, with no real shortcuts. Those methods start with "Notes on the E string" and involve sight-reading notes or guitar tablature notation, called TAB. Nobody you ever heard of can sight-read guitar music, and no offense to anyone but those kind of guitar lessons are basically a dead-end.

But just strumming songs at a party- isn't that easy enough for almost anybody?