I grew up saying this. As did lots of people around me. It’s being going on for years. Before the wankiest phrase ever “grinds my gears” poked its helmet out from the unwashed pubes of language to blink its eye into the sunlight of enlightened speech.
It’s made me speculate about it’s origination in Spanish. Having had to sell in past jobs it made me think that perhaps it’s effective at getting people to agree with you because it’s really hard not to start your reply with yes.
Thing is, it’s a valid sentence structure. It turns a statement into a question, and suggests that you aren’t sure about what you’re saying.
“It’s raining” is a statement. I’m telling you it is raining.
“It’s raining, no?” is an interrogative statement. I’m telling you I think it’s raining, but I’m not 100% sure and am soliciting further input from the listener as to whether you have more up to date knowledge of the current state of precipitation.
Now, I could say all that longform. But because I’m not Mr Logic…
… it’s far more convenient for both parties to suffix the statement with “no.” No?