TeX is a typesetting system that may be interesting to learn if you're interested in that sort of thing. LaTeX is a collection of TeX macros that are used while preparing documents, and probably isn't worth the effort to learn unless you have a specific need for it.
LaTeX has a number of positives. One is that it encourages the writer to focus upon the logical structure of documents, rather than the formatting. This is useful when preparing an articles or books for publication (when the publisher supports or accepts LaTeX). LaTeX is also good for certain types of technical publications, particularly those involving mathematics, since it handles the typesetting.
Beyond that, LaTeX is an unwieldy mess. If the standard macros don't do what you want of them, you either need to create your own or find some made by someone else. In many respects, it is like working with a library with programming. You'll need to figure out how to properly install those macros and you will need to figure out how to use them. Most people avoid the former by installing a rather massive TeX distribution that satisfies most of their needs. There is no way to get around the latter. You will have to read the documentation.
Once you have everything you need and know how to use it, there is the problem of creating the actual document. Tables and figures may not appear where you wish them to and there are times when you may wish to do something unusual, such as placing a wide table on it's own page and rotating it 90 degrees. Pretty much anything you may need to do is doable, but it is non-trivial to figure out. Not only is is non-trivial to do, but it is entangled in markup that is frequently difficult to read and may require a "compilation" to see the outcome.
None of that is meant to discourage you from learning LaTeX. There are cases where it is tremendously useful, it may be easier than the alternatives, and the quality of the product is usually quite good. The problem is that you pretty much need to know when to use LaTeX to reap the actual benefits.
> One is that it encourages the writer to focus upon the logical structure of documents, rather than the formatting. This is useful when preparing an articles or books for publication (when the publisher supports or accepts LaTeX)
This is the theory, but almost never been my experience. When I wrote for journals, and for my thesis, it was never the case where I could just use their style files and put in the content and the formatting would work out. Not even close. I always had to fiddle with formatting to get it to be good enough for the journal.
You are, of course, correct. I went down that road when hired to edit the LaTeX of a book for publication. Yet I also look at it as a case of LaTeX encouraging documents to be logically structured in the writing phase and doing the actual formatting later. It is, after all, a cumbersome process that is best handled when the text is ready. (Granted, that may be specific to the circumstances in which I used LaTeX.)
This is a problem with LaTeX, not TeX: whenever I've used plain TeX I've found the error messages extremely relevant and helpful; it's really pleasant to use. Yes you need to read the manual once to understand the conventions used, but after that, when typesetting your document, the error handling is very graceful and tells you everything you need to know.
Bottom line: it's a leftover from the 1980s. In the 1980s it was probably quite good. So was the Commodore 64, but you wouldn't use it to write your thesis on in 2020, now, would you?
It's a mess of multiple command line tools which run each other. None of which I understand or want to learn. tex, xetex, latex, xelatex, biblatex, texi2dvi, latexmk... What?
Its error messages might be very useful if you were running them by hand in 1985, instead of via 5 other tools. Literally these messages say things like "just type ? now", as if I'm doing this shit manually. No, I'm not, because I desire to use a computer to automate these tasks.
It gets in the way. If I open my article in a text editor, I want to see the title, author, abstract and first paragraph. Not 100 lines of backslashed computer blah. If I want to insert a picture, I don't want to have to write a paragraph of backslashed computer blah.
It's ugly. I don't want to see backslashes everywhere. I don't want to write `` to open quotation marks. I don't want to write \'e for é. I want to look at something nice when I write English.
Its model is that the markup specifies semantics, not syntax or layout. So you write \emph{} to emphasize something. This is bullshit. There are 100 reasons to use, e.g., italics: emphasis, foreign language, technical terms, etc. etc. Are we going to have a keyword for each of those? No. Just let me use italics. (Of course, they have that as well. Congratulations, you timewasters.)
Its culture is toxically up its own posterior. Oh, it's pronounced techhhh? Thank you for informing me, neccccchbeard. And if I have to read one more time "oh, don't use vertical lines in tables, just use \booktabs" in response to a question about HOW TO DO something....
Its toxic culture has infected academia. I've got referee reports saying "this wasn't written in TeX" as if that were a legitimate critique. PhD students are forced to learn it and spend nights crying and trying to make their tables work. Then they get Stockholm syndrome, become vastly proud that they know to write \ldots when they mean ..., and pass the filthy disease on to their students in turn.
tl:dr; Use HTML. Use Markdown. Use Microsoft Word. Hell, use RTF. Don't use TeX. Don't let your friends use TeX. Stop the madness now. Just Say No.
