Garak was initially intended by actor Andrew Robinson to be omnisexual. Indeed, Garak's first encounter with Bashir is very clearly sexually charged, which Robinson has stated was intentional. Though the pair would eventually become good friends, his primary interest in Bashir at the outset was sexual. That aspect of the character was eventually dropped for some disappointingly cowardly reasons.
The idea of a queer character on a Star Trek show was routinely vetoed by executive producer Rick Berman. Berman believed any hint of non-heterosexuality on Star Trek would have alienated a significant portion of the franchise's fan base across America in the '90s. It's an unsurprisingly reductive point of view, especially for a franchise as famous for its progressive politics and social messaging as Star Trek. It also flies in the face of the views of Star Trek franchise creator Gene Roddenberry, who was advocating for LGBT representation by the early days of Star Trek: The Next Generation in the late '80s.
It’s literally how the character was being played. Famed homophobe and asshole Producer Rick Berman demanded that Garak’s attraction to Bashir be played down because network snowflakes or something.
To your point, Bashir and O’Brian had a very close relationship.And while they had a massive bromance, no one thought they were gay for each other.
To add to what Flying Squid said, Andrew Robinson wrote a biography of Garak (and his up bringing in the shadow of Enabran Tain and his education by the Obsidian Order). In that book, Garak is VERY bi and there's strong hints that he could have been in a poly triad with a Cardassian boy and girl in Obsidian Order school... if only their loyalty and duty to the state hadn't complicated everything.
Especially if they keep getting defeated, which makes them less threatening each time they show up. Looking at you, Borg in VOY. Farscape's writers came up with Harvey specifically so they could have Scorpius make frequent appearances without diminishing his threat level.
Ok, now that the ugly argument is over, I think there's one fan favorite side character we must honor above all. Especially for his lovely singing voice.