Why is Summoner healing so nerfed, even compared to other DPS?

[Mayhemmer]

I'm still shocked that SMN Physic somehow survived as a terrible ability thru the ground up rework they gave to SMN and Arcanist. I hate to believe it was an intentional choice.

I'd wager it's because there's no realistic expectation for it to be anything more than what it is, just like there's no realistic expectation for a SMN to use it in content past level 35-ish. There's no real need for it to be addressed on SMN.