Even his single scene in The End (1978) as a baby-faced priest confessing Burt Reynolds, was a show-stopper.
Scott Baio and Adrian Zmed, with a tight muscular chest and six-pack abs.
And the producers knew it. All of his earliest movie roles -- Jory (1973), Troy (1973), and All the Kind Strangers (1974) -- featured ample shirtless shots. When he moved on to teen angst, dying in Death be Not Proud (1975), Ode to Billy Joe (1976), and The Death of Richie (1977), the beefcake completely overshadowed the gravitas of the plots.
Hs only significant bonding was in The Chosen (1981), about the romance between an Orthodox and a Hasidic Jewish boy -- otherwise his characters are busily falling for girls or dying. But the gay kids in the audience weren't paying attention to the plot anyway. They were waiting for the next shirtless shot.
After a few years in the post-teen idol sleaze-movie ghetto -- City Limits (1984) and California Girls (1985) were good only for fast-forwarding to the shirtless scenes -- Robby managed to establish himself as a grown-up actor. He continued to appear regularly in movies and tv through the 1980s and 1990s, gradually shifting into voice work (he was the voice of the Beast in the 1991 Disney movie Beauty and the Beast).