How am I supposed to know? I am sure there are excellent works from the STEM field written in word. But someone using latex has to at least some understanding of IT which is a good thing. Latex gives just a good first impression.
Based on former fellow students, I knew many would just stick to what they are fed and never get the idea to acquire knowledge on their own. And Latex could be just one of the things that shows curiosity and independent knowledge acquisition.
I think the refrain: “Never judge a book by it’s cover” applies here.
Our brains tend to associate good looking with well-researched when this isn’t always the case, hence the refrain quoted above.
So, if someone goes through the trouble of using a cumbersome typesetting tool like Latex to format a paper, perhaps they have made an important contribution that is worth setting aside 15-30 mins of your time to digest the thesis in its entirety.
If it's because of managing latex's complexity indicating some kind of ability, I can guarantee you that most people just copy paste and tweak stuff till it works.