OK Aestis, I'll bite
This is how I can most simply articulate it....the penalty sliders trigger animations...if you've ever seen a holding, a facemask, a DPI, etc. you've seen what they do with your own eyes.
Take that a step further...what is gameplay? It is a series of animations. If any slider changes the rate at which certain animations occur, what have you done? By definition: you've changed the gameplay. Change the animations, you change the gameplay.
When penalty animations trigger, they go through the player's penalty trait (which determines if it is called or not). This is realistic in the sense that uncalled penalties happen all the time (both in real life and in Madden). The problem is that raising the penalty sliders work in triggering more of those animations, but they don't necessarily result in more calls (likely due to the penalty traits).
If guys on the line are grabbing and holding more often (i.e. maybe you've raised the holding slider or maybe one of the block sliders)...that will have an affect on the manner in which the lineplay is shaped. Whether this has a dramatic influence on the overall manner in which your game plays out is very much dependent on the rest of your sliders.
Most people are more worried about the end-result rather than how they get there....penalty slider effects are typically more about the "how you get there" rather than the "end-result".
There are other thoughts out there about slider effects (gameplay and penalty) on CPU tendencies and so on. I have my own thoughts...but now we REALLY begin to get into the "just trust me"....I'm not going to do that here