I did give other sources before, you must have ignored them.
As for Alyx, I will explain why she is terrible.
While she does break a few stereotypes like the damsel in distress one and the sexualised object one, she absolutely represents another in full force - the "girl next door" stereotype. And quite frankly, I feel she started the "waifu" craze in video games. She's the original waifu bait character.
The Girl Next Door trope entails a female character that isn't necessarily a romantic interest to the main character (but Alyx is one anyway), but is kinda like that supportive friend that may not be a supermodel material, but is reasonably cute and often flirts with the main character and has a very playful relationship, romantic or otherwise, with the main character.
Alyx Vance is the EPITOME of this stereotype. If characters like Ivy from Soul Calibur or even Princess Peach are considered representative of and encouraging of teenage power/dominant kinky porn fantasies, then Alyx Vance is basically "emotional porn" - she is a character that, right off the bat, has this crush on Gordon, is always trying to play with your heartstrings whether you like it or not, and is designed for you, the player, to quite literally, have a crush on her. She is designed to make you feel better about yourself, like she's your cute, casual, normal girlfriend that you don't actually have. She's also just as much a "reward" for completing challenges as Princess Peach might be - for everything you do in Half Life 2, you are rewarded with a flirtatious comment, smile, and maybe even a subtle shot of her nice/cute/sexy, but not over the top ass.
And the cherry on top of this problem? Alyx's romantic advances towards the player are done through romantic advances towards Gordon - a character who never speaks. A character who never acknowledges her at all, because he is not programmed to by the developers. When you remove the element of the player getting an emotional turn on by Alyx, she literally becomes this obsessive high school girl who won't get over the guy who doesn't even acknowledge her advances - which is a degrading fetish in and of itself.
Pretty much every teenage guy fantasizes over perfect, huge breasted ladies and what not who need rescuing or are really aggressive, and some video games definitely use that to their advantage.
However, every teenage guy probably fantasizes over having a normal, "relatable" girl even more so, especially when they are lonely. One that tugs their heartstrings, one that they can go get an ice cream with and maybe hang out at the beach with during sunset, and then maybe start kissing and getting more intimate with behind the bushes.
Alyx Vance is designed to appeal to that emotional fantasy of having a "relatable", "conceivable" girlfriend (especially since she's portrayed as an awkward geek herself) for lonely gamers, except she bypasses the need to actually pay attention to her feelings, as her only feelings are for YOU. My emotional response to everything she says and does could be completely mean-spirited and disregarding of her feelings, but she is still gonna love me despite that. Like I said, ultimate waifu bait.
And if you need proof that Alyx turned a lot of people on by pulling their heartstrings and having a bit of sexual flair subtly sprinkled in there?
Rule 34 image counts for Alyx Vance and Ivy from Soul Calibur. Also most Alyx porn doesn't exaggerate or change her body as porn of most other characters like Princess Peach does, most Alyx porn is made using her cute in-game model that people got emotionally attached to for all of the wrong reasons, or a nude edit of said model.
And I'm not the only one who has this opinion of Alyx:
http://onemorecontinue.com/alyx-vance-half-life-2/
https://electriccartilage.word...male-character/
And here is an exploration of the concept of agency, that gives multiple examples - and rightfully criticises Alyx as a character who literally has no agency, OR ego:
http://exploringbelievability....ter-agency.html