tbh if I start worrying about poop particles in my day to day, I fear I'm one step closer to becoming a germaphobe. plus I feel if that's something that truly worries you, you'd start taking showers after each poop because clearly you will bring some poop particles with you when you leave anyway.

maybe this thread will end up being some kind of revelation, but I very much agree with the person you replied to. If I'm alone, I'm not bothered and the door may as well stay open

How much does the door help? I think generally people don't follow hygiene to the point that particles anywhere in the bathroom won't get tracked out of the bathroom. Don't get me started on people who touch their phones while eating...