The term Chicano Oldies is not trying to say Chicanos created soul music, It's a term to describe the Chicano experience, especially in California. These songs are a part of the soundtrack to many Chicanos lives. You'll see Grandpas and kids as young as 5 listening to these songs and keep this music alive. A lot of black kids who are not from California are complete squares when it comes to this music and will only learn about it if some shytty rapper samples a song. It's like the term "West Coast Funk", a lot of those funk jams come from bands from Ohio, NY/NJ etc., but that sound is associated with California. It's like White Boys from England listening to Motown and calling it "Northern Soul".
It's not just Oldies. Growing up in Cali you would hear Funk, Hardcore Punk, Heavy Metal, Freestyle, Alternative, House etc.. In L.A. you will see dudes with Gang Tattoos on their face and they'll be bumping Morrissey songs, that doesn't mean their trying to be white boys from Manchester. Music is Music.