Does it actually matter what the motive is? If Apple is making older devices slower as a side effect of something else, (and not informing the users who choose

Does it actually matter what the motive is? If Apple is making older devices slower as a side effect of something else, (and not informing the users who choose to update) is that really any better? And how can you ever prove they aren't aware of the effect and choose to do it anyways to sell more new devices?