> How else do you propose that companies monitor their sales and marketing efforts?

There are several ways:

  - Have a specific URL for each entry into the sales funnel - you see this on YouTube with things like "go to blahblahblah.com/witty-tag to sign up and get my discount"

  - Look at the referrer URL if you don't want separate incoming links per entry

  - Ask for a referral code when someone is creating their account - this allows you to track entry from people referred into the product

  - Have a field on the signup page where you ask this question instead of invading the user's privacy to get it

There are many ways that don't involve sticking a ton of trackers on a signup page, a page that by definition, all of your users must go through at least once and part of the face of your company. To me, it's not a good look that these trackers are there and invasive.