There is a certain prejudice — wait let me rephrase that: I’ve met with a certain prejudice against writing in the first person. As in “You can’t call rigorous an academic field which allows works in the first person” (source withhold to avoid embarrassments). But, to be blunt, this is complete bullshit from people who do not know enough about writing.
The preference for 3rd person comes from the attempt to avoid navel gazing, as in “me, me, mine”, as in a thought that has not outgrown a childish fixation with itself. In other words, when you are writing for other people to read, or at least when i am, you (i) try to talk things those people can get interested in, which includes assuming yourself not to be the centre of the world, and you thus avoid writing about exclusively you. Not that you don’t write about yourself. You just avoid doing it more than what’s strictly needed. While you are at that, writing in the third person can help, mostly as a reminder, because “I guess” is kinda tricky to turn into 3rd person.
That said, though, I can write the most me-centric gibberish in the third person. Beyond basic alphabetization stage, the voice you chose to write in is no proof of anything. Furthermore, when you begin to grasp the basics of philosophy and epistemology, but I mean the very barest crudest basics, you realize that, no matter how much numbers and statistics and “hard data” you put down, it is still your own point of view and it is still your own story. Then maybe you can do the opposite exercises writing in the first person to remind yourself that you are not talking about truth, but about concrete real (and therefore personal) experiences.
At least, that is why I do write in the first person.
And while I do some fairly idiosyncratic writing, when i go into «rigour-mode» i don’t get any less rigorous for the first person.