It shows me that they actually like me and find me attractive. If I were to approach a guy and he dates me, he might say yes but in my opinion that doesn’t mean he likes me or thinks I’m super attractive. I’m in the mindset that It just means he finds me acceptable enough to date me but if a girl he really likes comes around, HE WOULD APPROACH. therefore he might want her more or even cheat since he wasn’t the one who initiated with me in the first place
TLDR: because if a guy really likes you, he would approach you. If he doesn’t and you do the approaching, you most likely like him more than he likes you.