Edit: as phobic means you want to get away from something or don't want it to exist. Fetishising is the exact opposite.
If someone is arachnophobic that doesn't mean he wants to fuck a spider or undermine the identity of the spider. That someone wants the spider be gone because it is a spider.
Did you read the original reddit thread? Chasers are dangerous to the trans community. It isn't about being attracted to trans individuals, it's about specifically seeking them out for being trans and fetishizing them being trans.
Can you not see how this may look if you are the trans person in this relationship?
I'm not stupid, I know it means "fear of." Do you think Homophobes are "afraid" of gay people? What abiut transphobes? In the context of bigotry, phobia is used to refer to invalidating or undermining ones sexuality, gender identity, etc.
Literally talk to a trans person, or just read through that thread, it isn't difficult.
Talk to trans people about how they feel about lumping anti-trans views into the "transphile" category because rather than being hated outright, chasers simply prey on trans individuals and undermine their gender identity in a sickeningly fetishizing way.
I wrote a lot more than 1 sentence in the beginning and linked a good thread with a bunch of trans individuals discussing said topic. They aren't adding anything, just playing semantics with philic vs phobic.