Personally, any application that even collects personal data is problematic for me. Personal data of a user has a value, and a large repository of personal data, of millions of users, makes the company valuable too. Any data collected can be monetised, if not immediately (as part of the company's business model) or in the future (when the company is sold).

With Mozilla, for example, displaying sponsored links using Firefox Suggest ( https://blog.mozilla.org/en/products/firefox/firefox-news/fi... ) means collecting and sharing personal data (like search keywords, browsing history or bookmarks). This data sharing, with another company, could either be the raw data or the processed data. In either case, it is a problematic issue for any privacy conscious and politically aware user because either party or multiple parties will (or can) create profiles from the data. "Anonymous" data collection doesn't have any meaning here because with enough data points from a particular user, you can reasonably identify a user (either to track them digitally or to even to identify their personhood in real life, for legal or political reasons). This is easier to do so if you also combine it with data from multiple sources. (Which is what the US NSA programs with US BigTech are doing, and why these companies are so valuable today - Data is the new oil).