router99 analytics, when done well and not maliciously, is an important tool.
Let's say you have a website, where you sell things. You notice people come to the website but never make a purchase. So now you use analytics to see where the issue it by tracking the visitor across their journey.
Same for apps, they can use timezone to serve you region specific content, language to translate the website for you, look for your device processor to see if they should send you the heavy version of the website or the light version, etc.
It is a shame that adtech has monetized what used to be a way to make websites and apps better for visitors and users. The incentives are very distorted nowadays.