Frankly, she can no longer be a completely impartial & objective therapist
Aside from the fact that there never seemed to be any other psychologists or psychiatrists aboard besides Troi (and what kind of therapist doesn't have a therapist of their own?), Troi's empathy must leave her feeling all the various levels of sexual attraction to her from the rest of the crew. If she's not supposed to treat Barclay because he is sexually attracted to her, how can she treat any of the crew? Even Picard might have a low-level subconscious sexual attraction to her, yet she works with him regularly. I must conclude that Troi is able to be impartial about the crew's sexual attraction to her, if only because she's able to interact normally with the crew.