I don't know the stats off-hand but I imagine there's more MTF trans than FTM and I imagine the prevalence of gay is higher than lesbian.
By pushing the LGBTQ+, my hypothesis is that is removes more men seeking women from the dating market than it does women seeking men. Thus the supply of men is reduced and the demand for women is reduced as an overall impact of LGBTQ+.
Thus, were LGBTQ+ to not exist, would that make it even harder for straight men to compete for women?
Bear in mind that "true" LGBT is still a small part of the population. It's greatly exaggerated to give the impression that there are just millions upon millions of these people out there. Once you filter out people LARPing LGBT stuff for attention, the number shrinks substantially.