Yes and no.
I was watching this hour-long video by this YouTube called Ali Abdaal, who was explaining how he succeeded as a YouTuber, and one of his points was to not be afraid to lean into their (unfair) advantages. In other words, make full use of some "privilege" you enjoy which the rest of the competition may not to get ahead, and don't apologise for it.
A pretty face always helps at the start when you are trying to stand out in what is a very saturated field (tech reviews). But I don't think people are going to stick around and continue to support you by watching your content if they weren't any good.
Every YouTube is going to need a gimmick to draw in the audience. In iJustine's case, she's a (fairly attractive) female in a heavily male-dominated field, and I like that she brings something different to the equation. She doesn't go about tech videos in the same staid manner that other male YouTubers do. She dresses and acts pretty conservatively (you can't really accuse her of relying overtly on sex appeal - it's not like she poses seductively next to a Mac Studio in a bikini or something). She may not be an expert in hardware specs the same way someone like Linus may be (and I will argue that past a certain point, it doesn't matter because I can get that content from another tech YouTuber), and she probably won't last 5 seconds in a debate with Louis Rossman, but she still uses her tech to get work done, and I don't feel like she's faking her enthusiasm when it comes to Apple products.
So I watch her videos in addition to other YouTubers like MKBHD, Dave2D and Everyday Dad, and I am glad they each have their own style, and none try to imitate one another.
So yes, her attractiveness may have contributed to her success, and I see so reason for her to be defensive or apologetic about it, and I don't see anything "unfair" about this.