Do you understand how often websites change without asking the user? Websites are constantly being updated, algorithms tweaked, features being added and taken away. You seem to be taking offense to the fact that they're providing a different experience to different subsets of the userbase? Is that what you're trying to ban? What could that possibly accomplish?
If you don't have A/B testing, then websites are just going to do it the old fashioned way: collect data, make the feature change, compare the data. What does this solve?