Förstemann Squats

They are rubbish, barely even parallel, more a '1/2 squat'

Empty bar is generally too light to get your technique good.

Mike start with 30-40kg until you have your technique dialled.

Once you have, I recon you with probably be starting on 50-60kg

They are not rubbish. Thats how you squat when you are going heavy. Hitting your hamstrings on your calves would actually be a dangerous way to work with maximal weights and to some degree, cheating.

A parallel squat is when the crease of the hip is below the tip of the knee like this:

In power lifting competitions they often allow less.

If someone cannot squat an empty bar to full depth, then they suck at squatting. It shows that they lack the muscle control and proprioception. Even if someone is tight and inflexible, they should have the muscle control to be able to keep their backs tight and force themselves into a full squat.