Queer people liked the LGBT initialism (and the eariler GLBT) and embraced it because they disliked alternatives. Queer was introduced as a non-pejorative umbrella term at roughly the same time as LGBT, but for many, queer was still too painfully loaded to utter.
But the need for an umbrella term was great and became greater as "gay" stopped doing the work of identifying all or most members of gender and sexual minorities.
Nobody loved GLB, GLBT, or later LGBT, but they used them anyway because they had to use SOMETHING, and no other viable candidate made itself known. The English language required a word to express a concept people wanted to talk about, and the intitialism emerged as a result.
Even today, as clumsy as the intitialism is, people still prefer it over alternatives like queer or GSM (for gender and sexual minorieties), an initialism proposed a few years ago that flopped, even though it's more useful than LGBTQIA+, in that GSM obviates the need to add letters.
Why didn't it catch on? Who knows. I tried using it for a while, but people never knew what I meant, so I eventually stopped. Words aren't useful if people don't understand them.
Which is part of my longwinded answer -- people like and use homophobia because they know (or think they know) what it means. That was true even at the beginning, when it was first proposed as a definition of an actual phobia. The word works in ordinary English. People can get a sense of it without looking it up, even if their internalized meaning isn't quite right in terms of how others use it.
If a word is going to replace homophobia, we'll need people to believe they need the word, so they'll want to start using it, and we'll need the word to be understandable enough that writers feel comfortable using it outside specialized audiences.
Not saying that can't happen. But the odds of success for any particular proposed word are not all that great. Chances would improve if a proposed words looks and feels natural and clear by the customs of ordinary English usage.