I use other optimization and cosmetic mods too; thus, I need Fabric Mod Loader to load installed mods, as most mods I use mostly require Fabric and not Forge, and OptiFabric does quite not a great job; moreover, using OptiFine may result in some incompatibilities to some old and/or new mods, which is the main problem that I don't wanna use OptiFine with other mods, besides using it standalone.