These "people" are probably ones who have only ever done leg presses

. Their consequences will either come or they will be lucky and other people will pay the consequences for listening to them.
And "negative" can mean different things to different people. Some people think that the inability to use you legs for a week or more is a POSITIVE consequence, for instance.
Squats affect everything under the bar not just legs. Your spine gets to pay for it as well.