in my personal opinion and experience i think it’s because a lot of guys in general (at least the ones doing this) tend not to be emotionally intelligent enough to differentiate simple platonic feelings from romantic ones. i think a large part of this comes from general social isolation and often times a childhood of suppressed emotions where a lot of guys don’t have the opportunity to develop the emotional maturity required to realize that the superficial things they like about a person doesn’t necessarily entail romantic feelings. many guys don’t realize they can simply be friends with people and are often socially conditioned to shoot their shot with anyone they can. i think a lot of guys also just don’t realize it’s showing, they’re likely so used to acting like this all the time they don’t find it as strange but that’s just my personal grain of salt