There used to be several steel mills in the city but the numbers they employed were substantially larger. For example, the current ArcelorMittal Cleveland Works plant employs around 1,500 - at its peak when it was LTV, it employed 15,000. Half of it was razed and converted into a retail power center called Steelyard Commons.
As far as keeping a low profile? I think it's more of a matter-of-fact approach (as opposed to "WE'RE HERE, WE'RE QUEER, GET USED TO IT!"), as well as being integrated in mainstream society. Most major employers include sexual orientation in their employment non-discrimination policies and offer same-sex/domestic partner benefits. I've been open everywhere I've worked (mostly in the finance world) and brought my partner to company events and never had an issue. There's a monthly roaming happy hour event catering to men (G2H2) and women (WH2), each draws around 400-500. On several occasions they've turned down an establishment's offer to host because they know they wouldn't be able to handle the crowd. During the Gay Games, the corporate community contributed a lot:
Cleveland's lack of an identifiable gayborhood has more to do with the redevelopment patterns established in the early 1980s. When the Warehouse District in downtown was rediscovered by artists (and whenever that's the case, the gays are usually right there), gentrification ensued and rather than collectively relocate to one specific, the community dispersed to other areas like Ohio City, Tremont, Detroit-Shoreway, etc., all of which could be considered gay-friendly.