I've been using a system like that successfully as an academic (for some interpretation of successful). Started when I was a PhD student 25 years ago, and
have been maintaining it ever since. I was inspired by Niklas
Luhmann's Zettelkasten, whom I read voraciously as a teenager. I started as an undergraduate with hand-written index cards, but the obvious advantages of electronic files (fast search, cut/paste, easy backup,
doesn't need physical space) were immediately clear to me, so I moved to a computer-based system.
As I had already been burned by proprietary formats before, I use html as format from day one, every index card is html file in a separate directory. This has various advantages, including

- Easy consistent styling through css

- No WYSIWYG, separation of content and styling

- Easy to include code, which sits in the directory associated with the index card

- Easy to cross link

- Easy to backup

- Everything is under git control

- Easy to write shell scripts / programs that automate various tasks related to my notes

- Search with standard tools like grep

- Edit in my favourite text editor (Org-mode for quick drafting is especially useful I find)

- High quality rendering through modern browsers

- Easy to cut and paste into emails, whatsapp skype discord etc which is how I communicate with students and colleagues

- Easy to include other formats like images sound video etc

- Since the emergence of MathJax I can use LaTeX markup which means I
can cut-and-paste between my index cards, scientific papers and
lecture notes/slides

In summary, I'm super glad I didn't go super-hi-tech and stuck with marked-up text. It was the right choice! As Graydon Hoare once wrote: "[A]lways bet on text." How much work is it?
I spend 1-2 hours on average every day on writing. Is it worth my time?
What are the advantages for me that keep me using such a system?

- Structured, easily accessible 'idea store' / second-memory for later refinement and reuse. Refinement is maybe even the core: when I come back to a subject years later I come back from a different angle

- Helps writing introductory sections in papers, because I will have sketched my understanding of a subject already on an index card

- Helps writing related work sections in papers, because I accumulate work related to any particular index card's subjects over years

- Makes reviewing papers much easier, because I can cut-and-paste missing related work (most scientific papers are written by PhD students and post-docs who lack a historical perspective)

- Communicating with students: as an academic I get new students every year, and since they
got through similar stages and problems, it has become easy to reuse what I wrote in paste years

- The most important: cultivating a habit of writing down ideas, writing about ideas in a structured way, breaking them down into smaller parts etc, all of
which helps me to understand things better, and to communicate them more clearly to others

Is it worth it? I ask myself this question every day. I found that in
the first few years, I could always remember what I had written, so my
system was of limited use. That changed after about 8 years, when I
could no longer recall most of what I had written down, and then it
became rather useful, since I got 'new' and already pre-digested
ideas.

For me the biggest problem is that it has also become a procrastination device: I love writing. Whenever I am stuck with a work problem (and that happens a lot), I have a tendency to procrastinate by writing long entries on obscure subjects, unrelated to
my work. It feels like work, in some sense it is work, but it lets me avoid confronting high-priority tasks head on.