Well, anything that has an immune system, when able to fight off an invading bacteria, while being weaker right off the bat after spending energy to repair the damage done, it becomes accustomed to what it has to do in order to fight it off more efficiently if it should return, or change.
All living things change and adapt and strengthen themselves to the conditions they're presented with. Plants are no different.
Marijuana plants have already shown you all this whether you've watched it with open eyes or not... Stalks thicken because of wind, plants reach for sunlight. They adapt to the conditions they're presented with in order to ensure the survival of species.
I never said go crazy and start hacking away at the plant. I came to the conclusion that it's pointless to do it as well. Just from a different thought pattern than you may have.
If you're comparing breaking a leaf off a plant to a quadruped or biped breaking a limb, that's a gross over-comparison. Breaking a limb would be akin to taking the stalk of the plant and bending it 90 degrees to one side.
What I meant before by "speeding" up the flowering, I think you may have mis-interpreted also. The plant is going to flower until you remove it from flowering conditions, or brutalize it to the point it needs to re-veg. You're ultimately in control of how long you allow your plant to flower before harvesting it. So perhaps "speeding up" wasn't the correct term to use there.
I'm not advising people to trim leaves, nor am I saying it's a bad idea. Everyone has their own methods, and reasons for using them. You'd all be liars if you said there weren't loads of places around the internet with instructions to trim minor foliage.
Far be it from me to tell you what to do, but give people your opinion rather than telling someone else their opinion is wrong or bad, because whether you use the methods or not, many people have seen success as a result of this, and many have seen failure.
Edit: Also, I mean no disrespect by answering this question because the answer seems very pompous, but THG I learned that in High School Biology.