This discussion should probably be much, much longer... but I'll give you my take based on my experience as a queer person having worked in MANY industries from service to technology to government to private to recruiting/hiring to consultancy ad nauseum.
Generally it's not an industry or company that is homophobic but a person. This is why we have created nondiscrimination policies to protect from unlawful termination. It can be illegal, based on where you live, to fire someone based on Sexual Orientation or Gender Identity, but there are unfortunately many ways to subvert those rules.
93% of all Fortune 500 have a Sexual Orientation Nondiscrimination Policies, I'd say that's pretty good but that's only for Sexual Orientation. As you move down in revenue below the wealthiest companies, they are less nondiscrimination policies in place. Even some companies that claim to be LGBTQ+ friendly. So you can see why someone who has grown as a pariah and then later accepted by the majority of companies (because duh, money) would be skeptical of any company protecting their livelihood.
That is only one example of how a company can be LGBTQ+ friendly, another one that comes to mind is partner benefits (permission to attend company functions, relocation expenses, etc.). I personally have been prevented from attending a company dinner with my partner.
Again, this is just my take and I don't speak for everyone but I'm really happy to see a Job Board like this!