YABU
I use my phone for everything and if there's only one thing I take when I leave the house it's my phone.
It has all my cards - both debit cards for paying in Google pay and all my loyalty cards in the Stocard app. I have a purse with all the physical cards somewhere in the house but I could not tell you where it is off hand as I haven't needed it for literally years.
It has tickets for everything - bus/train/plane tickets are all on my phone; if I'm going to the cinema/theatre/concert/sports game, tickets are all QR codes on my phone so I don't have to worry about the physical tickets and they are accessible in seconds but also secure under my biometric locks
It the key to my house - we have smart locks that I can open with my phone so I don't have to carry keys with me, which is great since DD was always losing keys, now she just has to use her phone (though there is a manual failsafe if you don't have your phone)
It is my entertainment system - music/podcasts/TV/books/audiobooks - for when I'm on long journeys/out walking on my own
It's my organisation system - I have all my calenders/diary/schedules etc all there and my emails/texts are connected so if I get an email for an event then I can usually automatically add it to my calender in seconds. I can add reminders for almost anything to alert me at intervals useful to me. Additionally if I'm out and about and trying to organise the best route to/from somewhere I can look up train/bus/walking routes in seconds.
It's my mini computer - need to look something up? Need to check the opening times of the shop I want to go to? Need to book tickets for something? Need to transfer money to DD/a friend? All can be done from my phone in seconds no matter where I am
It also functions as a communication device - mostly text/WhatsApp (very rarely will I phone people) but means I can contact anyone if/when needed. I'm also a first aider at work so I always have my phone on me so that if I'm called to an emergency I can call 999 immediately (and in the last 6mo I've had to do that 4 times) if necessary rather that having to rely on someone else to either be nearby or available to call for me.
ETA: and all of that is done whilst my phone is permanently on silent - if I need it it is there but it doesn't disturb me ringing/chiming unless I actively check it.