Dominover

I have a hybrid bike with Shimano Gears and am referring to the front derailleur, and specifically the left limit screw.

I've seen this question/issue dotted around the internet so I wanted to run this by the experts.
My Front Left Derailleur limit screw connects to nothing at all. I can't upload pictures yet.
I've just realized that this is probably because, at least on this bike, the left limit screw is not needed. The Derailleur is clamped so close to the vertical seat post tube that the internal mechanism of the derailleur which would normally allow left or right movement to set the left stop limit, is already limited by the vertical seat post tube. It looks to me like the Derailleur has been fitted this way to forcibly guarantee the correct spacing between the left derailleur guide and the chain (around 1mm or so).

The right limit screw allows for left and right movement of the Derailleur chain guide, but for the reasons explained above, the left limit screw does nothing. Even when screwed right in, it barely touches the mechanism inside the Derailleur.
Are my assumptions about this correct. Does the way this derailleur has been mounted automatically set the left derailleur guide limit in turn doing away with the need for the left limit screw?
Also, is this common practice to build bikes this way?
If you want pics, I'll have to DM them to you. This forum doesn't allow me to upload photos because I haven't made ten posts yet.

Thanks.