-
I don't think so. I mean if they're super-tight from racing or training yes, but that will pass and most cyclists get tight hamstrings from riding in position, they're adapting innit. What lots of riding won't sort out is tightness in the hip from hard muscles around nerves that'll mess with the top of the pedal stroke (and other things).
I think for more people the limiter for getting low for TTs etc is in the lower back. Lots of riding can help that. And the right genes.
I think the trainers I know would say that 'being flexible'* can lead to better (smoother, more symmetrical) movement. Different people have completely different limiters though.
I'm pretty sure being able to touch your toes isn't an indicator of anything useful for cycling.
*massively non-specific and kinda useless phrase.