Because with stores, the evidence would be missing products. Very easy to see. With bugs like this, a million people could have abused it, or one. Either way that data is likely available to all who want it.
A better comparison is, store posted list of their customer’s addresses on the back door. No clue how many people walked by there much less if anyone copied it down.
Problem is that knowing the link between a person’s profile and their email now means you know the link between their account and their accounts in many other places. That information could be used to offer the person different prices at stores, attack them for being a minority or activist, to hack their account because their password was leaked from another site that uses that email,or all the other things these cumulative leaks add up to.
Not OP, but for me the issue is if you want to override the default and make it opt-out, especially sine the opt-out process isn’t that well documented, then you should realize that support is a necessary part of that process and fix problems as they arise rather than resorting to name calling and hostile behavior when something you published is broken. It’s a responsibility of taking on that kind of project. Either that or make it explicitly opt-in and give users a warning like with beta version opt-in notifications that the packages are not official and issues may not be fixed as quickly as the official releases.