Here's a simple counter-example. You're an e-commerce company, and in year 1, you can choose which js events/hits to track. For the sake of simplicity (and perh

Here's a simple counter-example. You're an e-commerce company, and in year 1, you can choose which js events/hits to track. For the sake of simplicity (and perhaps because prompted to do so by the Google Analytics tutorial) you only track product views (i.e. loading a product page) and conversions. In year 5, you now process 5,000 or 50,000 orders a day, and you're wondering what the click through rate of your products is when they come up in a search. That's your "question", which will help you figure out which 100 of the 100,000 products you stock your customer will be interested in (because it's 10x as much data as conversion rate). Guess what, those who installed Piwik and tracked the "impression" event/hit can now immediately play with it. You on the other hand have to start tracking it now and just missed on 5 years of data to explore which brands your customers like for example. It wouldn't have cost you much to track everything - maybe $1-10k/year for an AWS server to host the Piwik database (it's a bit costlier if you're with Google - $150,000/year for Google Analytics Premium + $15,000/year for BigQuery to be able to query the hit IDs, and only starts tracking on the day you activate it).