Comment by Nextgrid

It's not "companies" as a whole. It's a small department who comes up with these ideas and uses misleading, short-term metrics such as open rate or "cooking the books" by misattributing future revenue to their efforts ("this user who we spammed 3 years ago suddenly signed up - see, my marketing strategy is great, now give me a raise!") to justify their salaries. Their incentives are rarely correlated to those of the company, so every short-term trick that they can use to justify their salary is good even if it will be damaging to the company in the long term (by that time they'll already be on their next project with a successful achievement on their resume).