Let's be realistic here...
Magazine springs are designed specifically for the magazines they are intended to fit. To wit, a 7 round 1911 magazine is fitted with a 7 round 1911 magazine spring, as opposed to a 25 round magazine spring.
The springs are designed to provide adequate and proper spring tension essentially for the life of the magazine. Notice that I didn't say a steady or constant spring tension over its life...because the spring tension WILL change over use. Which is OK, so long as it retains adequate tension to meet the needs of the gun it is designed to work with.
A spring that is too strong or too weak will cause problems. But within these two extremes is a band of tension we call the "tolerance". Springs are designed to function within that tolerance for their design life for the magazines in which they fit.
You can compress them to the magazine limit and leave them compressed, or you can cycle them thousands of time within the magazine limits, it doesn't matter. Both will result in some reduction in spring tension over time (which will level out) and their final spring tensions will still be within tolerance.
THAT SAID:
This doesn't take into account poor design, poor materials, or poor quality assurance controls. Or even poor upkeep, leading to rust, for example. And yes, there will be the odd failure over time. But failures by cycling far out weigh failures by leaving magazines fully loaded, and over-compressing springs beyond their design limits will out weight leaving magazines fully loaded.
Like anything else about firearms, or anything mechanical for that matter, there is some amount of care and maintenance involved. Just like your car, for example, you pay attention to your gun and affect repairs when needed.
A wheel bearing is designed to last the life of your car under normal use. Sometimes, however, they go bad and you replace them, preferably with a quality part. But you don't summarily decide you're not going to load your car up with your wife and kids any more in order to prevent this from happening again because the car was designed for that.
The same applies for magazines...load them only to their limits.
NOW...
I mentioned "good engineering practice" earlier. You can cover a lot with that phrase, including this. However, the question when you do is "Is this a practical and realistic use, or is it just a 'feel good' measure?"
Given that the design life of magazine springs is extremely long, likely such a use would fall under the "feel good" category.
Personally, I think that if anybody seriously believes storing magazines fully loaded is harmful, even though cyclic stresses are of far more concern, they ought to just periodically change out ALL their magazine springs on whatever schedule makes them happy. A magazine spring costs less than a lot of combo meals at McDonalds.