Because it works seamlessly on all of my devices and has done so for years. Never encountered any issues and syncing happens within seconds.
It works great to have both enabled on iPhone/iPad however. No idea why they can't fix the overlapping fields in Safari.
https://1password.community/discussion/116898/in-big-sur-saf...
This is why I prefer to give my password to a company like Bitwarden and 1Password. At least, they have less incentive to be malicious than random dude on the store.
Perhaps time is more important for reputation than being incorporated?