It's not just Janeway that held to this standard. The other captains did too, particularly Picard and Kirk.
I'd have said Sisko was better at it than Picard. Picard did have a relationship with a subordinate. I don't remember Sisko doing that with any of the female officers on DS9, whether Starfleet or Bajoran. Kassidy Yates wasn't Starfleet.
Chakotay had a bunch of love interests, Janeway had a few, like Kashyk, everyone else had a few. Neelix and Kes had a sort of long term thing, Paris had a few love interests like Rain Robinson, and even Kim had a few love interests.
Chakotay had two love interests on Voyager - Janeway and Seven. He and Seska weren't a couple anymore, by the time the Maquis crew joined Voyager.
I absolutely never interpreted Janeway's relationship to Kashyk as anything but coerced or manipulative. She might have let her guard down a little, but most of that flirting was meant to get
his guard down so he would be less likely to figure out just what Voyager's strategy was against his people. I don't believe there was ever anything genuinely romantic between them. It was a really sick, toxic, manipulative thing. Any physical relationships Janeway had were either on the holodeck or with alien men (ie. Jaffen).
Neelix and Kes weren't officially officers and had no real place in the chain of command. They were basically passengers, working their passage by providing services such as cooking, trading, gardening, and nursing. Neither had any official rank.
Seven had no proper Starfleet rank, and the bulk of her "relationships" were either on the holodeck (with the fake Chakotay) or with Axum... and they weren't even physically on the same Cube when it happened. Of course there were officers who did want a relationship with her - the Doctor and Harry - but those were unrequited. TPTB should have built up the relationship with Chakotay more, rather than one episode with Seven and fake-Chakotay, one episode with the two of them stranded on a planet, and then BOOM! they're dating.
Tom and Harry had some kind of double-dating going on with the Delaney sisters, and a few other female crew who were so low on the totem pole that we never even learned their names. Harry couldn't even get a date with a hologram, and kept getting into trouble with the alien women he dated.
Tom's relationship with Rain had no bearing on the ship, other than the fact that he was flirting with her to get information and help - much like Kirk used to do, although I think Tom was much less cynical about it than Kirk ever was. Rain was never a subordinate to him; she could have said "yes" to a physical relationship and it wouldn't have made a bit of difference in the command structure of Voyager, even if they'd brought Rain with them. She was a civilian, not military or NASA. And in the end, Tom and B'Elanna were the only ones who ended up with a real, normal marriage and child (I exclude Tuvok, since his family already existed pre-Voyager).