I'm not sure how to answer this, so I picked 'unsure.'
I think they were both extremely lucky that Lindsey was tapped to get into Fleetwood Mac. That was one of those things that "stories are told, rumours" were literally written about.
They were just picking up some interest in Birmingham, AL when Buckingham Nicks came out, but they were dropped by their label Polydor-- as are most talented singer/song writers. Achieving success isn't just about talent--it's about luck. There's a lot of talented musicians on the planet--there's a few even on this board. Stevie and Lindsey were lucky
musicially to find each other. They happened to meet at a young people's group one evening.
Stevie was lucky when she got the tap to get into "The Fritz Rabyne Memorial Band." They were both lucky to get some exposure and get picked by "powers" to leave the group. They were fortunate to have the wherewithall to pursue BN. Then they were incredibly lucky to have their music heard by Mick who happened to be scoping out a potential need for a guitarist.
Would Stevie have become the success she is without Lindsey? Probably not. And Lindsey might not have achieved his own success without Stevie. There were a lot of stars aligning up for this whole "thing" to happen. It's not all about talent. It's not just about Lindsey. It's not just about Stevie. There's a LOT of luck involved. If they had no talent, nothing would have happened. Stevie and Lindsey both had a full measure of talent.