Makes perfect sense to me. Not every band needs a Wikipedia entry, does it?
Also, don't confuse their definition of "garage band" with "garage rock band" or "garage punk band," or, in other words, bands that play this particular style of music (i.e., trashy rock'n'roll vs. metal/numetal, mainstream rock/alternative, hardcore punk, emo, goth, mall punk, jam band crap or any other kind of music a band could play). This article is simply talking about ANY band that's just starting out. If you take it in the context that the article was intended, it makes perfect sense that not every band forming in their parents' garages or basements needs to try and set up its own Wikipedia page.