“I believe it served as inspiration for the Stairway progression, but I don’t see it as a rip off either.”
That’s my view too. The fact the 2 bands toured together adds a little more to the story, no doubt the song was part of Spirit’s set list. I am sure Page was at least influenced but it’s going to far to say he copied it. Too bad Spirit wasn’t better known they did some really good stuff and Randy California was a great guitar player
British bands ripped off US R&B mercilessly, sometimes with credit but often without. Led Zeppelin did this quite a few times. But this? Spitting on the sidewalk by comparison. Wolfe’s estate is being used in a money-grab.