Because (a) it would let you root your device, allowing you to do what you want with it (b) it would make these 400 vulnerabilities especially dangerous
(c) it would prevent most banking and finance apps from working.
Not "W[h]y [you] would ... want [to do this]" lol ;)
Just use the website.
Website for NFC payments? How?
Use the card.
Use an implant.
Not a fair comparison. ;)
You can use Xposed and Magisk to make them work
Best to use a bank which treats you like an adult and trusts you to make grown-up decisions about using a rooted device. Monzo fits into this category.