As the title says

I understand that Reyna is a great character to play for frags. Or how its cool to self heal as Phoenix. Same thing with Sage.

However, there is more to those characters than simply taking care of yourself.

In low elo lobbies, I see far too many people baiting as Reyna or Phoenix.

If you actually read their description, and play them the way they are meant to be played, they are the first in the fight. They use their utility to open up the site, and allow team mates to follow up on them.

Playing Sage is neat, because you can heal yourself. But if you heal yourself at 80 hp, and you have a teammate at 20 hp, the collective team hp is lower because of you deciding to heal yourself, thus putting your team in a worse spot.

Beginners should honestly look into something less frag heavy.