Are the tab grouping addons not useful, there's so many. I personally don't use them since I'm more of a 0 inbox and under 10 tab kinda person. I'd rather have 3 browsers open for different workflows.
I find it hard to navigate without being able to see the favicon and page name on the tab but if I had many, some sort of auto grouping extension might be immensely helpful.
Since it's publicly available and used widely enough, there would be 'those' people who like finding cracks in code or just have knack for looking deep through all kinds of data.
Not everyone is malicious and that part of humanity is something we have to trust in.