Actually, I use the Mail app for a single email account (my own private email). I just don't want to add all company email addresses to the Mail app. This way I have a better separation between work and private stuff. As in: when I check email in the Mail app, I am not confronted with work stuff.
Some of us think that the mail app is the inferior.
Search on the app uses my phone’s cpu.
search on the web site uses their cpu.