to understand their answer you have to realise that when you install lower springs you do not actually change the amount of suspension travel that your car has to any great extent. For the sake of a simple discussion what you are really doing is installing a really soft spring that compresses down really low by using up all its soft part. But because it has compressed down so far at its normal ride height (and is now almost out of travel that you need when you hit a bump) the last little bit of the spring is manufactured to be really hard (so rougher and potentially more dangerous when hitting bumps).
Even lower with std arms and mounting points is dumb. This is not a fun-police issue but an engineering issue.
Unfortunately this is not correct. A lowered spring i.e SSL compared to a standard spring is not a softer spring that compresses more.
Put a standard spring next to a lowered spring and you will see the lowered spring is shorter, hence the reason for requiring shorter shocks (which also have different/firmer bump/rebound characteristics) to make sure the spring stays captured at max suspension travel.
A lowered spring has to be stiffer because it has to control the same amount of (vehicle) weight but has less suspension travel to do so.
More modern lowered springs sometimes have smaller (and thinner coils) at the top, these progressive rate coils are designed to have a free length much like a stock spring, but the overall spring rate is still harder than a standard spring.
I run SSL springs in my VH with Bilstein shocks all round. at 50km/h it is extremely firm/hard ride but at 200km/h is soaks up the bumps real nice. I wouldn't recommend it for road use really. In my daily I run SL springs with shortened shocks and it's firm enough and low enough to sometimes cause issues on our lovely high quality roads here in NZ